Sciencemadness Discussion Board

picramic acid from picric

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Polverone - 28-1-2003 at 00:42

I know that sodium sulfide is used as a reducing agent for picric acid to form picramic acid, but to be honest I really don't like using sodium sulfide. It stinks and H2S is none too good for your health. Reviewing the threads on DDNP production at the E&W Forum, it seems that a lot of people have trouble at the stage where (according to KIBC or similar instructions) you reduce the TNP with homemade Na2S. But! When you mix NaOH and elemental sulfur in solution, you aren't making pure Na2S. You're making mostly sodium polysulfide(s) and sodium thiosulfate, and even exposure to the air will further oxidize the solution. I really don't know how the reducing power of this soup compares to a pure solution of Na2S.

Urbanski states:
Quote:
When mildly reduced, for example with sodium sulphide or hydrosulphite or with ferrous sulphate, picric acid is converted into picramic acid, a very useful intermediate in the dystuffs industry and a starting material for the preparation of diazodinitrophenol, primary explosive (Vol. III). Stronger reduction may lead to the formation of triaminophenol.


Unfortunately, I don't have volume III handy so I can't look at his DDNP synthesis. But I am confident (overconfident?) that I won't have trouble with the diazotization if I can produce picramic acid.

I used photo-grade sodium sulfide one time, added to an already-alkaline solution of sodium picrate, and obtained a dark red solution. I have been able to produce similar dark red solutions with ascorbic acid and fructose as reducing agents, which are both readily available and more pleasant than sulfides. But I don't know if I am in danger of over-reducing to triaminophenol. I can't even tell if I have triaminophenol. I don't know anything about it. Chemfinder is ignorant of it. No web pages give any information. Lange's Handbook of Chemistry doesn't list it.

Even picramic acid itself seems a mysterious substance. I have seen its color described as brown, yellow-brown, and brilliant yellow. In alkaline solution it (its salts?) are supposed to be red.

If any kind individuals have information to contribute about picramic acid, triaminophenol, or anything else mentioned here, it would be appreciated. Note that right now I'm not interested in later stages of DDNP preparation: I just want to nail the reduction and do it without the nasty and variable NaOH/sulfur mixture.

good information found!

Polverone - 17-2-2003 at 12:58

I remembered that picramic acid has been used as a dye, so the other day when I saw Fundamental Processes of Dye Chemistry sitting on a shelf I thought I would take a look inside. I found very detailed instructions on the preparation of picramic acid from picric acid.

It's a shame that I have such a big backlog of books I want to scan, because this book is full of interesting information. But since good results producing picramic acid have been so hard to achieve, I scanned the couple of pages and have added them in a PDF to the sciencemadness library. I bet you had forgotten we even had a library! Well we do, currently with an astounding seven items in it. I hope this helps those who have been questing for DDNP. I plan to apply the instructions myself one of these days (weeks? months?).

http://www.sciencemadness.org/library/

Question

Krypton - 18-2-2003 at 22:01

Why making picramic-acid ?
You can make many picramate-salt`s
(f.i. potassium and ammonium picramate)
directly from picric-acid without the way over picramic-acid in a double-step-synthesis (double-substitution in one step).
Substitute the -OH group with the Metal and reduce one NO2 group.

And also, be careful, when i remember rightly,
picramic acid are highly toxic (< 35 mg/kg).

Polverone - 18-2-2003 at 22:19

I was using "picramic acid" as shorthand for "picramic acid and its salts." But one reason to prepare the free acid instead of just salts is lower water solubility, which would make it easier to purify.

Purification may not be strictly necessary, but poor results have been consistently reported by people trying to follow fringe-literature instructions to produce DDNP. Eliminating extraneous variables by starting with pure materials seemed like a good idea for when I go to make my own attempt.

Synthesis

Krypton - 21-2-2003 at 00:58

The purification of picric-, picramic-acid... salt`s
conditional by high water-solublety is always not easy.
It don`t say, you get a bad product when not produced
by picramic acid.

Here a example for potassium-picramate.
Potassium-picramate are very long beautiful brown needles
which are somewhat sensitive to friction and shock
and which can be easy detonated by flame.
It`s a strong eplosive which have no real practical
significance.

I think it`s not nessesary to purificate the crude product
which have a good quality as well as don`t produced by picramic-acid.
The disadvantage is a bit lower yield, but the
expenditure is lower.

1-hydroxy-2-amino-4,6-dinitrobenzene potassium-salt.jpg - 57kB

Polverone - 21-2-2003 at 15:03

I was somewhat worried by the accounts I've read of people who have prepared picramic acid (or its salts) by improvised methods and found it burns poorly, with the smell of SO2. But I think I realize what that's from now: the polysulfides (perhaps even sulfides?) that you form by reacting sulfur and NaOH will yield extremely fine sulfur particles when acted upon by acid. There is probably very fine precipitated sulfur mixed in with the picramic acid/picramate.

That picture that you posted: is it of material that you have made yourself? It looks pretty clean.

[Edited on 21-2-2003 by Polverone]

What about

Boob Raider - 21-2-2003 at 17:37

using SnCl2 or FeCl2 in acidic solns to reduce the -NO2 on TNP to Picramic acid. It is used to reduce -NO2 to -NH2 in other reactions.

Microtek - 22-2-2003 at 05:56

But it is not a partial reduction. You will likely get triaminophenol with Fe/HCl. Of course you could perhaps mononitrate phenol ( though you would get both o- and p-nitrophenol ), reduce with Fe/HCl, and nitrate further.

Lets say

Boob Raider - 22-2-2003 at 09:05

we get triamino phenol, If we treat it with NaNO2 we should get the Diazo 4,6-diaminophenol. After this is seperated .... is it possible to oxidize the -NH2, back to -NO2 with say HNO3 or a persulfate etc. The only reason I am trying to eleminate the sulfide is ... some say it is -HS and some -2S. Then homemade NaSx contains all sorts of stuff in it. It is hard enough for me to accquire NaNO2, sulfides .... not a chance as they don't have much regular consumer application.

Boob Raider - 27-2-2003 at 20:28

Is this the color of Picramic acid. This was made by the addition of a soln of FeCl2 and HCl in Picric acid soln (made from ASA)

picramic acid 2.JPG - 116kB

PHILOU Zrealone - 23-3-2003 at 14:28

Reduction of TNP with Fe/HCl or with SnCl2/HCl will attack all NO2's of the ring no mather they are ortho or para; you will end up with 2,4,6 Triaminophenol!
In the contrary Na2S, (NH4)2S, Na2S2 reduction is very much specific and almost only reduce one ortho NO2!

You can kill a fly with a nuclear bomb or with pyrethrine; both methods work but difference is specificity and efficiency!

Also you seem to review your organic chemistry basics!
HNO2 will make diazotation of all NH2's from triaminophenol; it is also non specific/surgical reactant! Thus oxydation back to NO2 is impossible!

PHILOU Zrealone - 24-3-2003 at 10:32

Seem like I was tirred!
"Also you seem to NEED TO review your organic chemistry basics!HNO2 will make diazotation of all NH2's from triaminophenol; it is also non specific/surgical reactant AND IT WILL ATTACK EVERYWHERE! Thus oxydation back to NO2 is impossible!(POSSIBLE BUT NEED MUCH MORE PERACETIC ACID AND HEAT CONTROL)"

fritz - 30-11-2003 at 14:08

it´s possible to reduce one nitro-group of TNP with glucose. I never tried this but this reaction is used in physiological chemistry for testing the content of sugar in blood. So it should work.

1ml glucose sln. (8%)
4ml TNP sln. (1%)
1ml 3M NaOH
shaking and gentle heating. the solution should change its colour to red.

Equation:
3NaOH + 3CH2-(CHOH)4-CHO + NaTNP => Na-picramate + 2H2O +3Na[CH2OH-(CHOH)4-COO]

Vitamin C should do the trick as a reducing agent

Rosco Bodine - 1-4-2005 at 15:46

I too have been looking for alternative reducing agents for the reduction of picric acid to picramic acid .

Urbanski mentions that Ferrous Sulfate will reduce picric acid to picramic acid , but no details are provided .

Also it is likely that Ascorbic Acid , Vitamin C , is a good bet for the reduction , actually being a slightly stronger reducing agent than the Ferrous Sulfate . Solutions
of Ferrous Sulfate are green because of the Ferrous ion when freshly made but after exposure to the air , gradually are oxidized to the brown or rust colored Ferric oxidation state . Gradually adding some Ascorbic Acid solution will reportedly
reduce the brown Ferric solution right back to the green Ferrous solution , showing that Ascorbic Acid is the stronger
reducing agent than the Ferrous Sulfate .

I have not verified this yet by experiment ,
but read about it . Perhaps other of the dietary " anti-oxidants " may also be candidate reducing agents , for reducing picric acid to picramic acid .

Ferrous Sulfate is cheap as a garden supply item , so in terms of economy it may be the best reducing agent . It would be interesting to experiment with these alternatives to the sodium polysulfide , and see what sort of yields
and what purity of product improvements
may be achieved , to see what works best .

Sodium Bisulfite is another possibility .

[Edited on 2-4-2005 by Rosco Bodine]

UhhKaipShaltaBlet - 2-4-2005 at 04:07

This is sodium salt of picramic acid. Made by reducing TNP with Sodium Polysulfide.(SP prepared by dry method with NaOH and S.) No H2S after about 5 attempts was noticed. From 18.5g Picric acid prepared from phenol yield is 14.3g of high purity Sodium Picramate precipicated from water.

<img src="http://www.scimad.org/scipics2/SoPic.jpg" width="600" />

<!-- bfesser_edit_tag -->[<a href="u2u.php?action=send&username=bfesser">bfesser</a>: reduced image size(s); hosted image(s) at scimad.org/scipics2/]

[Edited on 18.12.13 by bfesser]

Rosco Bodine - 28-4-2005 at 14:52

In terms of simplicity and economy the method using the " polysulfide " reagent
made from the dry mixing and exothermic
melt reaction of S and NaOH is definitely
practical , and worth experimentation .
The experiments with that method were
not numerous to an extent for finding what exact proportions and conditions were optimum . The experiments were
only sufficient for identifying a general
method which would give worthwhile yields , by a few trial and error comparisons intended to improve upon
some of the earlier published black book
methods which give poor results .

The reducing agent which is produced by the high temperature melt reaction between S and NaOH is likely a mixture which is mainly two different sodium sulfur compounds , sodium hydrosulfide NaHS , and sodium polysulfide Na2S4 ? or Na ? S_(x) .

It is evident that the high temperature rapid reaction of the melt and lowered exposure to the air gives a product which
has more reducing properties than the product obtained by diluted solutions and boiling .

A patent US4156656 has compared the different compositions of the mixture which results for the reactions of alkali and sulfur under differing conditions of temperature and exposure to air . From the charted results it is evident that high temperature and minimized exposure to air results in a product much higher in the hydrosulfide which is the probable reducing reagent responsible for the conversion of picrates to picramates .
The " polysulfide " is probably a secondary
participant which may contribute to the reduction , although it is likely the polysulfide reagent could be more accurately named " hydrosulfide / polysulfide " reagent , when analysis of
its actual composition may be done .

The reaction is interesting because of the unknown nature of the stoichiometry for both the formation of the reagent , the reduction of the picrate to picramate ,
and the byproducts of the reduction .

I still do not understand exactly the reactions involved . I'll be damned if I can explain it to myself much less to anyone else how it works , only that it does work :D

For purification of the sodium picramate ,
I have read that the crude material
is dissolved in boiling water and filtered ,
and then dripped while still hot into a warm well stirred dilute HCl , which should result in the precipitation of the
only slightly soluble pure picramic acid
which is filtered out after cooling . The isolated pure picramic acid can then be used to produce whatever pure picramate
is desired by neutralizing with the base
for the desired salt .

Attached in this post will be the patent .
In the two following posts will be attached related files which shed more light on the soluble sulfide reducing reagents and reactions .

[Edited on 28-4-2005 by Rosco Bodine]

Attachment: US4156656 Preparation of Hydrosulfides.pdf (150kB)
This file has been downloaded 1935 times


Rosco Bodine - 28-4-2005 at 14:57

alkali-polysulfides

Attachment: alkali-polysulfides.pdf (574kB)
This file has been downloaded 3718 times


Rosco Bodine - 28-4-2005 at 14:58

polysulfide-aromatic-reduce

Attachment: polysulfide-aromatic-reduce.pdf (440kB)
This file has been downloaded 3008 times


chemoleo - 28-4-2005 at 16:22

Hmm, although very interesting, I am not sure how far I should let these off-topic discussions go. Isn't there a sulphide thread somewhere? Wouldnt it be better to post there and link to this topic stating its use?

Anyway. As I said, it's interesting that this in fact has been studied. We discussed this before, in the What was this substance thread! There are some pretty pics to look at, too. I still haven't gotten to the bottom of the mystery. The conditions the patent people employ are nearly identical to ours, so this should help (90 deg C, for 1 hour, no pressure, with NaOH/H2O/S).

Rosco Bodine - 28-4-2005 at 17:14

Hmmm , Here's what happened .
About 3 weeks after this topic was
posted by Polverone more than two years ago , I was not yet registered here
but anonymously e-mailed a reply to the subject in discussion in this thread .

The " dry method " for the unknown composition soluble sulfide reducing agent
was posted originally in the thread where
all of Mr. A's first messages appeared .
About a third of the way down the following page , is the dry method first described
for this experimental variation on the Zinin reaction .

www.sciencemadness.org/talk/viewthread.php?tid=470&*

Anyway , the post above in this thread two years later is the first feedback confirmation
by anyone else experimenting with the "dry method " so it seemed pertinent to reply here since the feedback was posted here .

At the time I was experimenting with the dry method of making the polysulfide reagent ,
the improved results were evident . However experiments remain to be done to determine what precise ratio of NaOH to S , and what quantity of the prepared reagent is optimum ,
for reduction of each mole of sodium picrate .

At the time of the experiments with the dry method , I did not have the references
above , which could have bearing on future experiments at optimizing the method .

The direction of the experiments was to increase the ratio of NaOH to S
in preparing the " polysulfide " reagent ,
until a point of diminishing yield would help to estimate the best ratio . And then
working with that best ratio , to first try using decreased amounts of the polysulfide ,
to a point of diminishing yields , in order to chart and identify the quantities
which would represent an optimized synthesis .

The next experiment which I have contemplated , but have yet to perform ,
is to use 16 grams of NaOH to 10 grams S , in the same reaction as otherwise described . My time for such experiments is often unhappily diverted to other business ,
so I simply wished to provide what information I had on the incompleted work in case anybody else wished to go further with that line of experiments which was producing improved yields of picramate .

[Edited on 29-4-2005 by Rosco Bodine]

Preparation from "Fundamental processes in dyes..."

pdb - 24-6-2005 at 03:17

For those among you who have followed the preparation procedure recalled below:

In a glass or iron container of at least 2.5-liter capacity, a solution of 10 grams of picric acid and 10 grams of 35 per cent sodium hydroxide in 600 cc. water is heated to 55°C., and to this is added, with vigorous
stirring over a period of 10 minutes, a solution of crystalline sodium sulfide in 100 cc. water. When this addition is completed, an additional 127.5 grams of pulverized picric acid is added in teaspoon portions, and simultaneously a solution of 220 grams of sodium sulfide in 400 cc. water is introduced, the additions of the two reagents being completed at the same time (within about 10 minutes in all).


It doesn't tell what is the concentration of the first addition of sulfide... I am tempted to computerize it according to the proportions of PA and sulfide in the next additions, but if this is wrong, I fear to reduce excessively PA and lower the yield.

Can you bring any precision to this process ?

Axt - 22-7-2005 at 06:11

"Lyons & Smith (Ref 5) prepd PAA in good yields by reducing PA with iron turnings in a very dil soln of Fe or Na chloride at 80-85°." PATR 2700 vol. 1, A241.

Ref 5: R. E. Lyons & L.T. Smith, Ber 60, 180(1927) [attached]

Attachment: reduction-of-nitroaromatics.pdf (600kB)
This file has been downloaded 2057 times


pdb - 1-8-2005 at 05:41

Rosco, in an earlier post (24Apr05), you mentionned a procedure to purify sodium picramate. Could you, by chance, recall where you found it ?

Also, sodium picramate solubility in water is about 1.2 g per liter at 20°C. Does anyone know the figure for sodium picramate ? Thx

Rosco Bodine - 1-8-2005 at 07:37

It was only a sentence or two in Urbanski or one of the journals maybe Industrial and Engineering Chemistry , I don't remember exactly but it was a recent reading when I had posted that bit of information . It is straightforward though
to isolate picramic acid from a boiling hot solution of sodum picramate by acidification with HCl or H2SO4 , which leaves the sodium chloride or sulfate in solution and precipitates the free picramic acid . There is a distinct color change from the very deep red sodium picramate to an orange yellow precipitate of free picramic acid in a very pale tinted supernatant . The precipitate is extremely fine small particles as is typical of a low solubility precipitate when rapidly precipitated , so it would aid getting a coarser more easily filtered product to do the precipitation at near the BP and add the acid dropwise slowly , to give the crystals some time to grow in the hot solution during the precipitation . IIRC , the color change is very pronounced , so the sodium picramate reactant actually acts as a built in color dye indicator for the progress of the acidification , providing a visual endpoint . You can actually work with fairly dilute solutions and not lose much in the supernatant over the free picramic acid , because the solubility is very very low especially after cooling , much lower than for picric acid for comparison . The solubility would seem to be about comparable to calcium sulfate or carbonate for example , very small . I don't have the exact solubility ,
but it is a low number .

pdb - 2-8-2005 at 00:54

I reduced PA to sodium picramate using the first method of Fundamental Processes of Dye Chemistry, which is a bit fastidious (11 portions of 1.16g PA to be added “simultaneously” with fractions of 5ml of commercial grade Na2S, 9H2O solution, while keeping temperature in a 57-62°C range). The process states to leave the solution rest for 10 hours after the last addition: I left it over for 24 hours (couldn’t do otherwise), and the once crystalline, dark-reddish precipitate of sodium picramate turned over time into a mud-like slurry, much more difficult to wash with cold salted water once filtered… I will nevertheless attempt to diazotize it into DDNP. However, in the case this extended rest period proves to have ruined my efforts (hydrolysis ? further reaction involving Na2S2O3 and/or NaOH ?), I am wondering how compulsory it is to closely follow the process, especially in the simultaneity of the addition of the reactants. I am aware that NaOH generated during the reaction may alter the picramate produced if in excess, and thus I am tempted to add Na sulfide dropwise to a PA slurry in water instead of adding PA to a sulfide solution.

Rosco Bodine - 2-8-2005 at 05:54

This is an area of experimentation which still interests me because of the improved density methods for DDNP and also the hydrazine / DDNP derivative lead salt which I have not tested . I also want to further refine the proportions and optimize the " dry method " preparation of the NaOH - Sulfur / hydrosulfide - polysulfide reagent , for reducing sodium picrate to sodium picramate .

I have a fresh batch of picric acid crystallizing now and hope to do some further experiments when time permits .
Actually the picric acid is itself a separate
experiment of a series I plan to do in evaluating the use of methyl salicylate as
an alternative to aspirin . It seems a bit more sensitive about the nitration times and temperatures and acid strengths than is the process using aspirin , but I believe once the optimum conditions are identified it will be a superior method .
My first experiment went well until about halfway through the introduction of the third nitro group , but I didn't go slowly enough or push the temperature high enough , or the acid mix was a bit too strong , so there was a mild runaway and boilover right at the endpoint where I had to quickly move the flask to a catch basin with a shallow layer of water to capture the overflow and save the batch .
Adjusting the conditions a bit should tame the reaction , and since the synthesis is not well known it intrigues me to formulate a reliable method . It seems to work similarly as with aspirin , but the reaction doesn't behave exactly the same and is touchier in the final stage . It will require a few experiments to identify the variables and formulate a good working method .

Joeychemist - 31-8-2005 at 03:09

The attached file is one of the listed references in PATR 2700 for Picramic Acid from the “Dictionnaire des Matières Explosives” (1902) by Daniel.

[Edited on 5-6-2013 by Polverone]

PAA REF-Page 615.jpg - 292kB

Swany - 8-5-2006 at 17:22

I took the thought of reducing with ascorbic acid to heart, and tried it. Tried, meaning placing some crude slightly basic Na picrate solution (some picric acid was perhaps in there as well) adding a few prills of NaOH, and dumping in some ascorbic acid. Shake, stir, and wait. After 10 minutes of nothing, I placed it in a warm water bath. This turned the solution to the characteristic dark-red and I am positive picramic acid (salts) were produced. After leaving it for an hour, the water bath had dried, and it was heating the tube on the pan, however, it was not boiling. It was a very dark colour now, no transparency. When a drop was placed in water the color was revealed to be a dark orange/red. I suspect that is slightly over-reduced?

Either way, the ascorbic method works, and I shall do some slightly more... controlled expirementation later.

Rosco Bodine - 8-5-2006 at 18:42

Well it's good that somebody has been curious enough to try vitamin C :D I have more good ideas than time for experiments , and I love it when you fellows check it out
and prove old Rosco right ! Great minds think alike ,
I tell you that's it :D And for when I'm wrong ....
well that's just the anomalous brainfart .

I suspect your orange coloration was from either unreduced
sodium picrate , or from free picramic acid due to pH being
a bit on the low side .

I have an untested idea that it could work best if you go a bit past neutralization of the ascorbic acid first with a sodium salt like ordinary baking soda , to the point
where it doesn't effervesce CO2 on further addition
of base . The warm concentrated solution of
slightly basic sodium ascorbate is probably air sensitive
like other reductants would be , so you may want to
minimize any overt exposure to air over any long period of time , keep the stuff closed up if it isn't going to be used right away for the reduction . And it might be good to use a piece of saran wrap and a rubber band over
the top of the reduction beaker , punch a hole or cut a slit for admitting the tip of the dripping funnel , to keep fresh air off the vortex surface of the reduction mixture .
The reduction should be done very gradually , running in the ascorbate solution while it is warm , into the prewarmed sodium picrate solution , pretty warm depending on the induction temperature .....there will
be a temperature where you can probably control the exotherm by rate of addition ....so the reaction proceeds
fairly rapidly but in a controlled way . Let it keep stirring
past the end of the addition for the time it takes to start
cooling down significantly on it's own , and then let
it sit in the refrigerator or a bath of melting ice overnight .
Sodium picramate will be a very dark burgundy red
precipitated fine prismatic crystal , a very dark maroon
or oxblood color ....and it is an intense dye much more
dark colored and soluble than free picramic acid .
The crystals should be so fine it will almost look like
mud on the filter , but in strong light it will glitter profusely revealing the crystalline nature plainly .

[Edited on 9-5-2006 by Rosco Bodine]

Swany - 9-5-2006 at 15:29

What are the products of the oxidation of ascorbic acid, so I can balance an equation. Would a gross exess of ascorbic acid violate the reaction, of simply make sure it gets reduced. Do we belive it could over-reduce to triaminophenol?

Either way, after I recrystallize some TNP...

Rosco Bodine - 9-5-2006 at 16:53

If I have it right , it simply loses one hydrogen
when reduced . I take it that " monodehydro " ( ascorbate ]
means " minus one hydrogen " :D ,
probably the atom and not the molecule ....
I have to be at least half right :D

This is from Wikipedia

http://en.wikipedia.org/wiki/Ascorbic_acid

Uses
Ascorbic acid is easily oxidized and so is used as a reductant in photographic developer solutions (among others) and as a preservative.

Exposure to oxygen, metals, light and heat destroy ascorbic acid, so it must be stored in dark and cold and not in a metal containment.

The oxidized form of ascorbic acid is known as dehydroascorbic acid.

The L-enantiomer of ascorbic acid is also known as vitamin C (the name "ascorbic" comes from its property of preventing and curing scurvy). Primates (including humans) and a few other species in all divisions of the animal kingdom, notably the guinea pig, have lost the ability to synthesise vitamin C and must obtain it in their food.

Ascorbic acid and its sodium, potassium, and calcium salts are commonly used as antioxidant food additives. These compounds are water soluble and thus cannot protect fats from oxidation: for this purpose, the fat-soluble esters of ascorbic acid with long-chain fatty acids (ascorbyl palmitate or ascorbyl stearate) can be used as food antioxidants.

The relevant European food additive E numbers are: E300 ascorbic acid, E301 sodium ascorbate, E302 calcium ascorbate, E303 potassium ascorbate, E304 fatty acid esters of ascorbic acid (i) ascorbyl palmitate (ii) ascorbyl stearate.

[edit]
Antioxidant mechanism
Ascorbate acts as an antioxidant by being itself available for energeticaly favourable oxidation. Oxidants (scientifically referred to as reactive oxygen species) such as the hydroxyl radical (formed from hydrogen peroxide), contain an unpaired electron and thus are highly reactive and damaging to humans and plants at the molecular level. This is due to their interaction with nucleic acid, proteins and lipids. Reactive oxygen species can 'abstract' a hydrogen from ascorbate, which becomes monodehydroascorbate and soon gains another electron to become dehydroascorbate. The reactive oxygen species are reduced to water while the oxidized forms of ascorbate are relatively stable and unreactive, and do not cause cellular damage.

Dehydroascorbic acid (DHA) is one of oxidized forms of ascorbic acid. It is actively imported into the endoplasmic reticulum of cells and generates the oxidative potential found there. Protein disulfide isomerases are known to reduce DHA back to ascorbic acid, oxidizing their disulfide bonds in the process. Therefore L-dehydroascorbic acid is a vitamin C compound much like L-ascorbic acid. As a result of different contents of crystal water (hydrated water) there are different forms of DHA: the waterfree bis-DHA and the mono-DHA*H2O. In literature often mono-DHA without hydrate water molecule is used. Oxidized forms of esterified ascorbic acids can be numbered at C(5) or C(6) atoms and the (free) chemical radical semi-dehydroascorbate or semidehydro ascorbic acid (SDA) to the group of dehydroascorbic acids.

[Edited on 10-5-2006 by Rosco Bodine]

Swany - 10-5-2006 at 14:55

Some solutions were mixed, about 50mls of Na picrate soln. at RT, along with some slightly-warm sodium ascorbate solution. The solutions were dumped togeather in a erlenmeyer flask, stoppered loosely, and set on a low set hot-plate. Upon return 15 mins later, it was happily boiling slowly and was a very dark color, appearing alomst black. This was placed in an ice bath overnight, and was placed in the freezer for a bit to cool to 0 before filtering. I obtained a small (.25g) amount of sodium picramate. It is dark-red, maroonish color, and quite fine-grained. The crystalline structure is not particularily dense. I have not calculated the soluabilities, but this seems to be an OK yeild given circumstances and mistakes. Either way, it burns. :P I have yet to do a reduction with actual measuring.

I will add this to HCl in order to create free picramic acid and NaCl. This will then be acidified furthur, and a NaNO2 solution will be added at OC. If a diazo-product resembling DDNP is obtained, I dub ascorbic acid proved and worthy as a reducing agent for TNP.

Rosco Bodine - 10-5-2006 at 15:33

When you get to the diazotisation , there is a very
specific temperature window and concentration of
reacting solutions and addition rate which produces
suitably dense crystals of DDNP .....where any other
conditons only produce a low density amorphous
powder form which is not suitable for dets .

Relevant excerpt from Urbanski 3 , page 203 :

The effect of conditions of preparation have been thoroughly examined by Smolenski
and Plucinski . They found that at a diazotization temperature as recommended by
Clark , i.e. 15 C , the product pours with difficulty . Conversely , diazotization at a
higher temperature ( 25 - 45 C ) results in formation of a product with a density of
about 0.82 .

Smolenski and Plucinski prepared dinitrodiazophenol in the form of free flowing crystals by applying the following reaction conditions :

A solution of 320 g of sodium nitrite in 2 l. of water is added to a suspension of 1000 g of the sodium salt of picramic acid in 8 l. of water . Next , 6 l. of 5.5% HCl
is added dropwise for 2 hr. , stirring continuously . The initial temperature of 20 C rises to 25 C . Completion of the reaction is determined by means of starch-iodide
paper . The product is filtered off , washed with cold water and dried at 35 - 40 C . Its yield amounts to 80 % of the theoretical .


Blaster at E&W has described a diazotization procedure modeled on the above method described on the following page , with pictures .

http://www.roguesci.org/theforum/other-explosives/435-ddnp-t...

[Edited on 10-5-2006 by Rosco Bodine]

Swany - 10-5-2006 at 16:52

Yes, I synthed the amorphous form. When I actually do a measured reduction, I will prepare it via the afore mentioned method.

EDIT: well, at least I thought it was amorphous. It is powdery, and fairly free-flowing, although not crystalline as was the ideal product. It did, however, burn extremely fast more like the second type. As fast as any flash I have ever created, I suppose.

[Edited on 11-5-2006 by Swany]

Rosco Bodine - 11-5-2006 at 07:34

It is something I would have to check my
patent references , but there are ways to
further process the amorphous form and
make use of it in mixed , coprecipitated
compositions , where DDNP functions as
an accellerator for deflagration to detonation
transition mixtures , useful particularly with
those polynitrated polylols which are almost
but not quite primary explosives by themselves .
Things like mannitol hexanitrate , inositol hexanitrate ,
even PETN , co-crystallized in admixture with DDNP result
in powerful det fillers which are DDT primaries
and are reportedly relatively stable and safe
enough for practical use .....although not as
storage stable at higher temps as military grade
systems , still good enough for commercial use .

DDNP in 50/50 mixture with picric acid forms a eutectic
melt a bit below the bp of H2O , which can be detonated
by compressed granular DDNP more easily than picric
acid alone , and the eutectic is more brisant than picric acid alone . Such a combination could have usefulness
in improvised dets where raw materials are a limitation
but a pretty high performance device having reasonable stability and safety could still be achieved .

DDNP also forms a reaction product with hydrazine
which is reported to have usefulness . So there
is a lot which can be done further with DDNP , even
if it is obtained as the amorphous product and not
used directly . IIRC , when a binder like dextrin is
used to form a pellet of the DDNP , it will self-confine
and undergo DDT at a certain mass quantity , going
high order after ignition even in the open , same as
is true for many other primaries which are a bit slow
on self-accelleration , but the rise is more rapid for
DDNP while it makes the transition to high order ,
so it does the job of DDT completely in subgram quantities under the right conditions of confinement ,
better say than mercury fulminate for an example of
another " slow starter " which also then climbs the
velocity ramp to DDT .

Swany - 11-5-2006 at 10:00

Interesting... I happen to have some MHN on hand, and I belive I will try a co-precipitation and then attempt to detonate it as a primary, and just play with it.

Once again, after I recrystallize my TNP, I will get some numbers and figures to work with for the reduction, and hopefully results. I feel empowered. :P

Rosco Bodine - 11-5-2006 at 13:46

Here is one of the relevant patents .

It looks like the nitrated polyol like ETN or MHN
is a relatively small percentage of the DDNP composite
and is simply used as a graining binder , densifier
sort of function for the DDNP . A similar idea as
is used with bullseye smokeless powder / acetone
syrup to make AP putty , only more powerful .

Basic lead picrate mixed with nitromannite would probably
do the same trick , and would be easier to make than the
DDNP . I have never experimented with these composites .

Attachment: US2396152 DDNP - nitrated polyol mixtures.pdf (282kB)
This file has been downloaded 1239 times


Rosco Bodine - 11-5-2006 at 13:58

Here is another patent which relates to
the hydrazine product of DDNP ,
and analogues based on hydrazine derivitives .
There is a series of metal salts possible
from reaction of the metal nitrate with
the product from DDNP and hydrazine .

This patent is published by the same
inventor as who disclosed the azo-clathrates .

Attachment: US2728760 DDNP hydrazine product.pdf (123kB)
This file has been downloaded 1437 times


Axt - 11-5-2006 at 22:37

Havn't seen this come up in any forum, apologies if it has but it is an excellent review of DDNP, synth and explosive properties.

Clarke, L. "<i>Diazodinitrophenol, a Detonating Explosive</i>" Industrial and Engineering Chemistry.; 1933; 25(6); 663-669. [attached]

[Edited on 12-5-2006 by Axt]

Attachment: diazodinitrophenol - a detonating explosive red.pdf (956kB)
This file has been downloaded 3238 times


Boomer - 11-5-2006 at 23:48

Two points:

"It looks like the ... ETN or MHN is a relatively small percentage of the DDNP composite"

Rosco is right as usual, while it stays a good primary with more than its weight of (per)chlorate, I found that an equally big percentage of e.g. MHN hinders DDT in many substances. HMTD and TATP need much bigger charges to reach DDT if mixed 1:1 with MHN, and even silver fulminate stops detonating in small specks.
IIRC it was a mix of MHN and tetracene that detonates from heat. Considering how bad lead picrate is as far as run-distance to detonation is concerned, I doubt LP/MHN will be a good choice.

"... only produce a low density amorphous powder form which is not suitable for dets "

This quote from Rosco I don't understand. The article Axt posted (which *was* posted before but don't ask me where) specifically says both forms have the same strength measured by sand crushing ability. The fine powder may be harder to load on automatic high-speed machines, but since we hardly make thousands of detos, I personally don't mind a fine powder. Plus, will a fine powder not make DDT easier (smaller run-distance, less needed)?

Rosco Bodine - 12-5-2006 at 01:18

For any initiator to work properly it needs to
have the ability to compress into a pellet
which doesn't re-expand but holds together
in its pressed form . Some of the crystals
actually crush during pressing and wedge
the uncrushed material in a casing . But
an amorphous powder won't usually form
a stable pellet on pressing , so it won't be
practical . The det you press today may not
fire properly after a couple of days , if the
pellet of initiator swells and crumbles as
it sits . Reenforcing caps are required for
securing the lower density DDNP in the casing
and keeping it at a density where it will
fire properly . This is exactly why I quit
experimenting with DDNP and said I was
not really impressed with it , was the difficulty
with low density material . All of my experiments
with initiators have shown that a certain " grit "
or mesh size of fine crystalline material just
always seems to work better , no matter what
initiating compound is being tested , than is
the case for powdery dustlike materials .

Now weight for weight the total power may be
the same for several grams of either material
in the sand test . But in terms of the sharpness
of an initiating impulse produced by the miniature
" ribbon charge " that is the pellet of initiator pressed
directly in contact with the column of base charge ,
there is a huge difference and advantage for the
more dense material . Initiators do act as a miniature
ribbon charge which is a basic shaped charge on
a micro scale ...so the same charge density benefit
applies , as would be the case for a brick sized
ribbon charge .

Swany - 13-5-2006 at 11:31

6C6H8O6+C6H3N3O7 -> 6C6H7O6+C6H5N3O5+2H2O

Look good? That is a reaction mechanism where the ascorbic acid looses 1 hydrogen. The ratio-by weight- of ascorbic acid to TNP is 4.61:1, so I think 5:1 ascorbic acid to TNP is acceptable, no?

Rosco Bodine - 13-5-2006 at 17:24

Yeah for the theoretical , 6 moles of Na ascorbate
for each 1 mole of Na picrate .

A couple of per cent excess of the theoretical
requirement of ascorbic acid for picric acid
reduction is probably sufficient excess ,
and on that basis , use 4.7 grams of ascorbic acid
for each 1 gram of picric acid .

You can do the slightly alkaline neutralization
by using a per cent or two excess of the sodium
salt required , for each of the acids .

mole weight for ascorbic acid is 176.12
mole weight for picric acid is 229.11

Swany - 14-5-2006 at 16:40

Well, it all worked. Due to a hurried addition of HCl to the diazo reaction, I belive I have amorphous product, and I will weigh that yeild to determine how I did.

Everything went according to plan, and I am optimistic.

Is there any way that one can utulize the non-freeflow form of DDNP?

Rosco Bodine - 14-5-2006 at 18:40

Could possibly densify it by dissolving in acetone
and then adding toluene ....or naphtha , or xylene,
maybe even white gasoline , maybe methanol
......I'm not sure ,
I'd have to check some references .
But I think there is a cosolvent precipitation method
for densifying the stuff .

Or you could make a methanolic extract of hydrazine
from hydrazine sulfate and experiment with the
hydrazine derivative , and their salts .

Swany - 14-5-2006 at 19:07

Hydrazine sounds constructive, though, my reagents will need serious purifying before I will get any decent yeilds from it.

Too bad I messed up the DDNP batch, eh, live and learn. I am still midly amused the vitamin C actually worked nicely. Good idea ;)

Do you think it would be worth it to make a thread about DPNA? That stands for diazoperchlorate-3-nitroaniline, and apparently is quite fun. Or, perhaps 2,4-dinitrobenzenediazonium perchlorate> Basically, I am interested in aromatic diazo salt primaries. Does that make any sense? :P

Rosco Bodine - 14-5-2006 at 21:29

I can just see the checkout at the drugstore ,

A thousand aspirin tablets , and a kilo of vitamin C ....

yepper , got one hell of a headache , and feel a bad
case of scurvy coming on :D

That'll do it .:D

About the new thread , no I think there is already some extensive stuff posted on it , search and find .

Boomer - 15-5-2006 at 03:17

I still don't get it, according to the above ref also the amorphous stuff presses to 0.86 g/ccm, IIRC even under a low 240 bar. Since it cannot be dead pressed, I don't see why you cannot utilize it just the same. Notably in electric dets which are completely sealed, hence the reenforcing cap is not needed, neither is the "crumbling-out" of the pellet a problem.

I believe if pressed enough, you will get an equally good initiation pulse, and that the only advantage lies in the "free-flowing" property for easy filling my machines.

Swany might test this batch (so it is *not* wasted), and then the next batch (done Rosco's way) to see if it makes a difference in e.g. plate dent testing.

Rosco Bodine - 15-5-2006 at 06:37

I never tried something easily initiated like MHN as
a base charge for the low density DDNP , where it
would probably be fine . I most often use picric acid
as a base charge , which requires a pretty intense pulse
to initiate . And even for HMTD which has a really
good literature report of performance in unreenforced caps , it can be difficult and take a fair amount , which
is the way it looked for me concerning DDNP of the
fluffy variety ....nothing to campare with say lead azide
for example . So given the difficulty of making DDNP
and the light sensitivity , it just didn't impress me nearly
as good as say lead azide or the azo-clathrates . I
did not extensively test the DDNP , because its performance never seemed to come close to literature
references , and one good example of the exaggerated claims extended to the 50/50 eutectic with picric acid
which was reported in a patent to be fuse sensitive ,
which after my test I was forced to laugh and ask
in what quantities ...ten grams or twenty ? :D
So I just never really was much impressed with the
stuff . But I am sure it has potential usefulness if
the correct conditions are met , I just lost patience
with experiments with DDNP and moved on to other materials , thinking it was too fickle for my liking ,
not really a good general initiator . Azo-clathrates
are so slick I became enamored of them very quickly ,
and lost interest in alternatives which may still have value , particularly if made under more optimized conditions . I'll stay out on a limb here and say the
crystalline form still makes a difference no matter what
the literature may report to the contrary , and I would bet money that tests bear that out .

Swany - 15-5-2006 at 15:02

Yes, I also ran into some trouble as my Na picramate was not totally dry, and was thus still basic and some of the first amounts of HCl were titrated against NaOH, not Na picrate :(

So, the yeilds are a bit off! I will venture to guess I recieved >5g.

Azo-clarthates do look quite interesting, and at one time, I was inspired to try them! I am caught between hydrazine and aromatic diazo perchlorate salts. :P

Rosco Bodine - 15-5-2006 at 17:47

Sodium picramate is such an intense dye and so much
redder and more soluble than free picramic acid that
it can act as its own color change indicator for marking
the titration endpoint when adding acid . IIRC you can actually make DDNP by first titrating the sodium picramate solution until you get a color shift to a very pale yellow supernatant solution over a pigment fine
precipitate of the less soluble free picramic acid which
is an orange brown dull and drab color much different from the intense deep oxblood red color of sodium picramate . The diazotization can then be performed
simply by adding sodium nitrite solution . Adding it
all at once gives the amorphous product , but I would
expect that by using sufficient dilution to get the free
picramic acid back into solution , or entering solution
in the reaction zone at a temperature that is correct
for the limited rate of addition of the sodium nitrite ,
that crystallization might be slowed sufficiently for
better crystal development . It is probably all
about reaction rate control and solubilities which
determines the crystal form as much as any order of addition , although it is not certain that this is so .
It may be that the only way to get decent crystals
is to follow the Urbanski outlined method in every detail .
It could be worthwhile to try different dilutions and
see how the titration method may perform at similar temperatures and reaction volumes and addition rates
as is described by Urbanski .

Mason_Grand_ANNdrews - 21-6-2006 at 09:57

I`ve read a document, picramic acid was made by the reduction with iron. I guessing iron is corrosive, but didn't think this method will work better.

Dissolve 1g of picric acid in 100 ml of glacial acetic acid at room themperature and this is stirred until all is dissolved. 0,5 g of finely powdered iron is added over a period of 24 hours and the mixture is stirred papidly. The liquid is stirred until the mixture turns to slight dark red and all iron is dissolved. The liquid is than evaporated by distillation.
I belive the result is better obtained when the mixture is diluted with H2O and the crystals are precipitated by cooling to 0 gegree celsius.

Is the result picramic acid and will this method give a purer product ? Some hints would help. ;)

[Edited on 21-6-2006 by Mason_Grand_ANNdrews]

[Edited on 21-6-2006 by Mason_Grand_ANNdrews]

Rosco Bodine - 21-6-2006 at 13:43

That's one huge waste of glacial acetic acid , IMO .

Reportedly ferrous sulfate will work in aqueous solution .

Axt - 21-6-2006 at 17:15

Quote:
Originally posted by Mason_Grand_ANNdrews
I`ve read a document, picramic acid was made by the reduction with iron.


Near bottom of first page in this thread I've attached an article giving conditions for 96% yield from PA using water/NaCl/iron turnings. I've never tried it, though looks easy enough.

0.5g NaCl, 50ml water, 25g PA & 18g Fe, heat for 5hr @ 82-85°C --> 96% PAA

[Edited on 22-6-2006 by Axt]

Rosco Bodine - 21-6-2006 at 19:31

That reaction mixture will be a slurry , like porridge
probably and will likely be required to be stirred
for the duration of the reduction .....and it will probably
need makeup water to be added periodically to maintain the volume .

The reacted iron will probably be the black oxide which
is quite insoluble and will be intimately mixed with the
picramic acid which is also nearly insoluble , perhaps
a signifcant portion of the product being present in combined form as ferrous picramate . To isolate the
desired product in pure form it will be necessary to
dilute and digest the spent reduction mixture with an acid in order to convert any oxidized or combined iron
to a highly soluble ferrous salt which will be easy to
filter away from the free picramic acid . Using pool grade hydrochloric acid of 31.45% concentration for
this purpose 65 ml would be the minimum amount of
theory , but using 75ml would probably be better ,
and even as much as 100 ml to 110 ml would liklely be fine for a diluted spent reduction mixture . This digestion
will probably require heating the mixture to or near the
boiling point and stirring for a few minutes to complete ,
and the mixture can be cooled and diluted further before filtering . The excess of HCl is a good idea since it
will accommodate the likely oxidation of some of the
ferrous chloride to the ferric chloride from exposure to air and heating and stirring , and will keep all the iron in solution as the ferric chloride is even more soluble than the ferrous chloride expected as the initial product of the digestion .

My german isn't good enough to pick out whether this
was described in the article ....but take my word for it
that if it wasn't it should be . And HCl may not even do the trick of solubilizing the oxidized iron .....nitric may
be required , or the addition of a nitrate salt to the HCl
may provide sufficient nascent " aqua regia " to do
the trick . Sometimes the oxidized iron particularly if
it is the black oxide can be surprisingly " inert " as if
all the " fight " was gone from that poor iron after
being so brutally oxidized :o , ravaged by hordes of
rampaging horny nitrobrutes .

I have done a few of these reductions of other nitro compounds using iron , and FeCl3 as a catalyst ,
and driving the reaction directly with an HCl drip
while heating at the bp and stirring violently to
keep the iron in suspension and the insoluble nitro
compound emulsified in the mixture .

It may be as simple as it seems from the article
just stirring the slurry of the iron and the picric acid
since for this reduction the nitrocompound is soluble ,
but the isolation of the picramic acid product is
what will be the the trick .

The_Davster - 21-6-2006 at 20:03

Why not just basify to get the soluble picramate, filter out the iron and iron oxide, then acidify the picramate to get back the picramic acid? Seems much easier. Can even control the size of the picramic crystals this way.

[Edited on 22-6-2006 by rogue chemist]

Rosco Bodine - 21-6-2006 at 20:11

You could try that , but I'm betting on an unfilterable
ferrous hydroxide or other complication with that approach because there will likely be enough soluble iron which drops out when you basify ....but maybe boiling would break it up .....so yeah good idea . Would require greatly diluting the
mixture , maybe to a liter or two .....I'd have to check the solubility of sodium picramate at boiling .

One thing for sure , you will have a separation to look forward to . So .... does anybody speak enough german here to see if the article sheds any light on this ?

[Edited on 22-6-2006 by Rosco Bodine]

The_Davster - 21-6-2006 at 20:15

I don't know how picramic would behave here, but with adding a bit of peroxide to ferrous hydroxide, no matter how much of an ooze it is, will make it much easier to filter iron (III) oxide. However oxygen is also released which might reoxidize the picramic.

Rosco Bodine - 21-6-2006 at 20:25

That article may be a german journal parallel publication
of an american journal article , because the authors
have american names and the laboratory work was done
in the US . Maybe sombody could find the english version published material if it was also published in an english language journal . Axt ?

Anyway , the separation using a base will depend on how finely divided is the oxide and if it is heavy enough to settle
out so the rest can be decanted . Any iron hydroxides
mixed with the sodium picramate would be no problem
since those will readily be sent into solution as chlorides
by HCl , while the picramic acid will precipitate on acidification .

I still think the acid separation will be more straightforward ,
and sulfuric alone or sulfuric with a bit of nitrate or nitric
should work fine too . It would make for some interesting experiments to find what works best .

[Edited on 23-6-2006 by Rosco Bodine]

Mason_Grand_ANNdrews - 24-6-2006 at 10:05

I was also thinking about how to obtain picramic acid.
Is that correct, the addition of finely
powdered sulfur to a warm mix of picric acid/NaOH solution would be sodium picramate ?
I guessing, serveral steps will needed. The NaOH/sulfur should neutralised and filtered complete from the slurry ;)
to prepricate the sodium picramate.
You are right, the described method with the iron powder was somethimes crap. Very low yield.
What is the result, dissolved phenol in NaOH solution was nitrated with dilute HNO3, second step - 70% HNO3.
A article says it is 2,4-dinitrophenol. This will be not a sodium salt ?
Even though, that during the formation of variably results by ratio dinitrate/trinitrate, HNO3/concetration by acid, H2SO4/HNO3. Why not picramic acid by 4-chloro-2,6-dinitrophenol. :P



[Edited on 24-6-2006 by Mason_Grand_ANNdrews]

The_Duke - 24-6-2006 at 10:41

Quote:
Originally posted by Mason_Grand_ANNdrews
I was also thinking about how to obtain picramic acid.
Is that correct, the addition of finely
powdered sulfur to a warm mix of picric acid/NaOH solution would be sodium picramate ?


That will not work.

Mason_Grand_ANNdrews - 26-6-2006 at 10:12

I have just done a search on the net for information about the result but but i didn`t found
somehwat. Nasty H2S will bubble off sulfur is added. I belive that will work when the slurry is serveral cleaned
and contents are removed.
Sulfur/soluble in CCl4
NaOH/neutralization by HCl
I hope that will work. Picric acid is added to NaOH solution at 60 degeree celsius until
addition is saturated. Finly powdered sulfur is stirred to the mixture until nothing will dissolve.
To this, some dilute HCl and any ml of CCl4 will stirred in the mix. I hope the result can be obtained when,
the liquid is careful vaporizised or the slurry is diluted with water in a ratio 1/3, filtered and the crystal are prepricated
by cooling to 0 degree celcius. I'm not sure, alternative ways to obtaining the results;) are adding a large access of CCl4 to the mix and this will prepricate the picrate, adding HCl to neutralizing the salt and the picramic acid will prepricate or the mix will than diluted with H2O and this is cooled to 0 gegree celsius.

4-chloro-2,6-dinitrophenol
5g of 4-chlorophenol is careful added to a mix of 60 ml 90-95% HNO3 / 120 ml 96-98% H2SO4 and the mix
is careful heated and stirred over a period of 4 hours to 100 degree celcius. The crystals of 4-chloro-2,6-dinitrophenol are prepricated by adding 1000 ml cold water to the mix.
Several washings thoroughly with water will clean the crystals. As a possible alternative to that, 4-chlorophenol will be refluxed for two hours yield a purer result and don`t have remains of a mononitrate of 4-chlorophenol.


[Edited on 27-6-2006 by Mason_Grand_ANNdrews]

Rosco Bodine - 27-6-2006 at 08:56

Quote:
Originally posted by Mason_Grand_ANNdrews
I have just done a search on the net for information about the result but but i didn`t found



Searching the net should have included searching this thread :P including the link posted near the end of the first page , concerning Mr. Anonymous " dry method " for making
the Sodium Polysulfide reagent . The experimental method
is pasted below .


As promised, there is some info I can share regarding the polysulfide route to picramic acid. I will preface by saying there are better, more efficient uses for picric acid, from what I have observed about the usefulness of DDNP, which is what I presume is the ultimate object.

A good quality of deep red crystalline sodium picramate in good yields is possible via the sodium polysulfide reduction of sodium picrate. Several times I have repeated the experiments and found that slight adjustments in reaction conditions can improve the results, so I have not yet determined what conditions are optimum.

Please feel free to tweak the general process, if you want to do the work. The polysulfide reduction is quite similar to the synthesis described in your library. The problem that I have seen in the online descriptions of the polysulfide reduction, is a lack of detail about the correct method of preparation for the sodium polysulfide reagent. A thorough, intimate mixing of the correct proportions of NaOH and sulfur, being first thoroughly mixed as DRY ingredients, which absorb moisture from the air very gradually, darken in color, and initiate a spontaneous highly exothermic reaction while being stirred is the required approach for producing a good polysulfide reagent. If atmospheric moisture is low, a trigger mister can be used to get things going. The idea is to get the reaction going from a stirred dry powder which becomes crumbly as it warms and darkens and then a drop or two of water is added, the mixture stirred very well and a few more drops of water added, whereupon the reaction then proceeds on its own to form the polysulfide very quickly as a dark red but transparent liquid which looks bright yellow in thin layers. The stoichiometry for reactions involving polysulfides is not fully known. The goal is to get a good reduction without a great precipitation of elemental sulfur as a contaminant. My own theory is that if the alkalinity is just right, the higher polysulfide which is decomposed in the reduction can be converted to a lower polysulfide and remain in solution, instead of precipitating free sulfur. The polysulfide may possibly even reform from its fragments after acting as an unstable intermediate compound in the reduction. I am uncertain that the actual mechanism for the reaction involving polysulfide is even known, beyond the knowing that it just works somehow.

The following is from my old lab notes, with commentary ideas included.

Experimental:

On a hotplate stirrer is placed an 800ml beaker and with stirring, 22.9 grams, (.1 mole) picric acid is dissolved in 400ml boiling water. Heating is stopped. To the stirred still hot solution is added a solution of 4.2grams NaOH (.105 moles) in 25ml water.

comment: easy solution was noted so less water may be useful in subsequent syntheses.

While the slightly alkaline sodium picrate solution is cooling, a sodium polysulfide reagent is prepared as follows:

NOTE: All of the following procedures should be done with good ventilation, toxic gas is produced.

Into a 100ml beaker is placed 13 grams NaOH fine prills and 10.1 grams powdered sulfur (flowers of sulfur USP) Using a glass stirring rod the granular materials were manually mixed dry as thoroughly as posssible, and as the stirring was continued the mixture began to take up moisture from the air and darken in color slightly, and the physical texture changed as the mixture became stiffer and more difficult to stir. The particles become adherent to each other and the mixture begins to warm.

A couple of drops of water are fed from an eyedropper onto the stirring rod and stirred into the mixture, then two drops more, and stirring is assertively done between dropwise additions to blend the very gradually increasing moisture into the reactants. The induction of a highly exothermic reaction occurs concurrently with the slight dampening of the mixture which may need to be stirred yet a little more if any "dry lumping" is observed. The pasty mixture gets really hot and darkens quite rapidly, with an evolution of intense "sulfur fumes" from the melting and reacting sulfur. Hold the beaker by the upper rim where it is cool and do not get burned by touching the walls of the beaker near the reaction mixture. The addition of water two or three drops only, in each addition may be continued portionwise, with stirring between these small additions, in order to maintain the heat by reaction and heat of dilution, until a dark red transparent solution results. The hot reaction mixture should become a thin and mobile enough liquid that further mixing and dilution can be done by manually swirling the beaker lightly.

Once the pasty mixture has cleared to a hot solution (melt would probably be more accurate description), then gradual additions of water in increasing amounts should be made by the eyedropperfull until the volume of the resulting solution is about 40ml volume. If a dark red melt clear of solids fails to form completely on its own heat of reaction, at this point DO NOT add a lot more water and "boil" or a partly crystallized failed to complete reaction mixture will probably result.

If 1 or 2 ml of added water is insufficient to "kick" the reaction by heat of dilution, then supplemental heat will be required to drive the reaction to completion, before further dilution to a volume of 40 ml. This dilution should be sufficient to prevent the reagent from crystallizing upon cooling. Keep the polysulfide reagent from contact with the air after it is prepared. Air may degrade and cause precipitation of elemental sulfur from the polysulfide reagent if it is left standing uncovered. The prepared reagent is put into a separatory funnel and supported over the still warm sodium picrate solution prepared earlier. A piece of plastic wrap is secured over the top of the beaker with a rubber band and the plastic wrap is puntured in the center to admit the tip of the separatory funnel. This is done to exclude air from circulating freely around the surface of the solution in the beaker during the addition of the polysulfide solution. A seal is not needed here, a loose covering is sufficient.

To the stirred sodium picrate solution at 44 degrees centigrade, was added the sodium polysulfide at a rate of one drop per second to one drop per two seconds, with stirring continued for one hour. The mixture was then covered to the complete exclusion of air, and allowed to stand in the cold overnight, chilled to 5 degrees centigrade, filtered and the crystals of sodium picramate and the filter paper and filter cake were further dried by placing on a stack of paper blotters. The crystals were dark red prismatic and very fine granulation, and were used without further purification for the diazotation reaction.

Mason_Grand_ANNdrews - 28-6-2006 at 09:20

Nice work, if you want to know some chemical information what any explosives are souluble in water. This will advise some to the extraction and solublity in chemicals.
2-nitrophenol 21 g/l
2,4-dinitrophenol insoluble, around 100 mg/l
2,4,6-trinitrophenol around 10 g/l at room themperature, 11g/l at 20 gegree celsius
sodium picrate and picramate around 5g/l to 6g/l
Looks like that the way by NaOH are always exotherm and will require a precise calculation by weight to the NaOH solution. Well known are any content of NaOH in the result can pumping out moisture from the air and the result will melt away. :P

[Edited on 28-6-2006 by Mason_Grand_ANNdrews]



[Edited on 29-6-2006 by Mason_Grand_ANNdrews]

Rosco Bodine - 28-6-2006 at 10:04

Quote:
Originally posted by Mason_Grand_ANNdrews
Nice work,


Not optimized , but close enough for " government work ":P
and a lot better than the old " black book " method .

I don't know where you get your solubility figures ,
but IIRC sodium picrate is * more soluble * than picric acid ,
and so are the lower nitrophenols .

Quote:

Looks like that the way by NaOH are always exotherm and will require a precise calculation by weight to the NaOH solution. Well known are any content of NaOH in the result can pumping out moisture from the and the result will melt away. :P


Something is lost in the translation there . I do not
understand what you are saying .

Mason_Grand_ANNdrews - 29-6-2006 at 08:37

Sorry about the lost word in the post, some login trouble. :(
Any solubility in H2O will tell the safety data sheets but to exposives, precise infos will hard to get that what exactly solublityes are. I would guess what you read somewhere will not correct ;) always.
Also i belive, picrates are better obtained by a carbonate and will be better to store. Some stuff will decompose to fast on the open air by water.
Whats going on topic ?

Axt - 4-7-2006 at 23:57

Quote:
Originally posted by Rosco Bodine
but IIRC sodium picrate is * more soluble * than picric acid ,
and so are the lower nitrophenols .


Picric acid = 1.4g/100ml @ 30°C (PATR 2700)
Na-Picrate = 5.58g/100ml @ 30°C (JACS; 1939; 61(12); 3302-3303; attached)

[Edited on 5-7-2006 by Axt]

Attachment: Solubilities of Sodium and Potassium Salts of Nitrophenols and Related Acids.pdf (257kB)
This file has been downloaded 1839 times


Mason_Grand_ANNdrews - 20-7-2006 at 08:56

Thanks for uploading the PDF. I guess some methods will have interest. I belive there are more possibilities to obtain picramic acid. I will thinking about.

Rosco Bodine - 24-1-2007 at 08:36

There are some related patents which should be
listed as also having application to the production
of picramic acid by way of sulfides / polysulfides .

While these patents were published with the focus
upon selective reduction of one nitro group in order to produce aniline or nitroanilines from nitro or polynitrobenzenes , the same reduction reagents and methods are applicable to the selective reduction of one of the nitro groups of picric acid to produce picramic acid .

US1878950

US1689014

US1765660

A highly relevant article

Rosco Bodine - 27-1-2007 at 18:29

The preferential reduction of nitro-groups in polynitro-compounds. Part III. Picric acid and 3 : 5-dinitro-o-cresol. An almost quantitative preparation of picramic acid
Herbert H. Hodgson and Edward R. Ward
J. Chem. Soc., 1945, 663 - 665


This study showed an optimum molar ratio of sulfur on a molar basis to the nitro compound of 2.3 to 1 ......

which is precisely the same ratio as found to give nearly quantitative yields in another reference for a similar reduction , example 2 of US1878950 .

So the somewhat preliminary molar ratio of Sulfur to picrate
of about 3 to 1 which I used in my dry method polysulfide ,
is not wildly different nor greatly excessive , even though
I knew it was not yet optimized ....it was generally in the ball park . And my direction of next increasing the alkalinity
tracks as well .

The Hodgson article also seems to agree with my own
thinking on the matter of the hydrosulfide of sodium being
the actual reducing agent .

There is a Thiokol corporation patent ( yes the same SRB propellant folks ) , US2796325 , which is very informative
about how NaOH reacts with Sulfur , and how polysulfides
of various sulfur content or " sulfur ranking " are gradually
reduced on long heating to lower and lower ranking , until
the hydrosulfide is reached .

Attachment: J[1]. Chem. Soc., 1945, 663 - 665, .pdf (344kB)
This file has been downloaded 2202 times


Rosco Bodine - 27-1-2007 at 23:48

Some further details on this method are on page 12 of the attached file , which reviews the Zinin reaction in general .

Attachment: The Zinin Reduction of Nitroarenes , H. K. Porter.pdf (777kB)
This file has been downloaded 2762 times


concerning the origins of the " dry method "

Rosco Bodine - 28-1-2007 at 00:32

When I was trying by trial and error
to work out a simple method for quickly making
an active polysulfide reagent and came up with
the technique of thoroughly mixing the dry solids ,
gradually moistening and initiating a highly exothermic
reaction to a melt then gradually diluted .......

it appears I was " reinventing the wheel "
with regards to that idea .

As it turns out it was indeed ancient art , patented 1913 ,
US1068769 , and that patent reissued later after it expired .....so it evidently was a useful method .

Anyway the patent is attached for the original " dry method "
as it has been called by others ....and seems appropriate .

The analysis of the result of the reaction , given in the patent
is incomplete IMO , as the 36.98% of so called " Free sulfur
which is soluble in water " is no such thing at all ,
but would be a combination of reducing sulfur compounds
which do have solubility in water probably Na2S2 and NaHS
for the most part . The actual analysis of these mixtures
will be variable , depending upon the alkalinity relative to the
sulfur content , the amount of water present , the temperature of formation and how long the mixture was heated ......and especially how much exposure to air the
mixture received . The minimizing of air exposure also
minimizes the formation of thiosulfate and sulfite , to the
benefit of a higher yield of " reducing sulfur compounds "
in the mix . From all the patents and references I have
studied ....the conclusion remains with me that the actual
composition of these " polysulfides " is ambiguous and
variable ....depending upon how they are made and the
ratio of alkali to sulfur .

Update: I have done some numerical analysis and studying of the percentage analysis provided by the patent , in order to " reverse engineer " the likely reaction quantities which would have produced that analysis I believe is in error .
It appears that the analysis provided would have applied
to a reaction involving on a gram basis for example ,
40.4 g NaOH and 55.16 g Sulfur ....
and the dubious percentile figure stated for " Na2S " when
*added* to the equally dubious " soluble sulfur " percentage , sums nicely to about what should be the expected yield of Na2S4 ....or a blend of alkali and sulfur rankings of several polysulfides approximating Na2S4 as an average for their composition , or on a gram basis 65.45 g ,
of the Na2S4 equivalent . This analysis and conclusion was
based in part on the information disclosed in a more modern Thiokol corporation patent US2796325 .

In my own estimation , a much better polysulfide reagent for performing reductions would require additional alkali sufficient at least to bring that Na2S4 ranking 4 equivalency component down to Na2S2 , and possibly even lower .
I am continuing to review the available literature to gain further insight and make an educated guess about the
correct proportions for polysulfide reagent to be used in the next Zinin reduction experiment . I am not certain of this , but it appears that it may be best to first make the higher ranking sulfur compound such as Na2S3 , Na2S4 , or even Na2S5 , since the higher sulfides form more rapidly ....and then after the higher sulfide has formed , to add more NaOH to form the lower sulfides desired with longer heating in the absence of air . This strategy might reduce the side reaction
which produces the byproduct sulfite and/or thiosulfate ,
tying up 10 to 20% of the sulfur as non-reducing sulfur compounds . The patent process above has a byproduct
loss of sulfur of 11.8% as non-reducing sulfur compounds ....
so it actually isn't a bad starting mixture for subsequently added alkali to make it a useful reducing reagent . The inventory of alkali lost to the byproduct formation has to be accounted for in calculating the requirement of additional alkali for adjusting the composition of the polysulfides to
a lower sulfur ranking .


[Edited on 30-1-2007 by Rosco Bodine]

Attachment: US1068769 Original Dry Process Sodium Polysulfide.pdf (174kB)
This file has been downloaded 51437 times


Sickman - 29-1-2007 at 23:27

I found a journal abstract that would agree with FRITZ post earlier in this thread that glucose is a valuble (and cheap):D reducing agent for "alkaline picrate" (sodium picrate) forming picramic acid directly as a major byproduct.

The following is that abstract from PubMed:

"Effect of glucose upon alkaline picrate: a Jaffe interference.Viraraghavan S, Blass KG.
Department of Chemistry, University of Regina, Saskatchewan, Canada.

The reactivity of glucose in aqueous alkaline picrate was investigated by spectrophotometry and polarography at 25 degrees C in 0.51 mol/l sodium hydroxide. Thin-layer chromatography and infrared spectroscopy studies have conclusively identified the presence of picramic acid in 5:1 and 10:1 glucose picrate test solutions incubated at 25 degrees C. The polarographic data of an alkaline picrate blank with a concentration of 0.284 mmol/l, show three well-defined nitro group reduction waves with approximate half-wave potentials of -0.62 V, -0.78 V, and -0.93 V and a fourth broad wave appearing near -1.31 V versus a saturated calomel electrode. The addition of glucose to alkaline picrate resulted in a decreased diffusion current for reduction waves 1-3, with little change in reduction wave 4. The reactivity of test solutions containing glucose:picrate in 1:1, 2:1, 5:1 and 10:1 molar ratios was investigated at varied time intervals between 10 and 180 minutes. The absorption spectra of a 10:1 glucose:picrate solution shifted from 356 nm to 375 nm and a broad tailing shoulder absorbance formed in the 450-600 nm region. An orange coloured minor product, separated by thin-layer chromatography, was observed to fluoresce. The maximum excitation and emission wavelengths were 318 nm and 545 nm, respectively. A major, red-coloured product was isolated and identified as picramic acid by infrared spectroscopy. For 10:1 glucose:picrate test solutions incubated at 25 degrees C, picramic acid formed within 10 minutes. Within the first minute, the colour was observed to change from yellow to orange and then to red.

PMID: 2329319 [PubMed - indexed for MEDLINE]"

Hope it helps with the pursuit of an easy way to picramic acid!:P I wonder what the yield of picramic acid would be compared to the other products of the reaction? I'm still trying to interperet the reactions described in this absract, I guess a few tests to see what we get couldn't hurt.

Sickman

a theory distilled from the references ......

Rosco Bodine - 30-1-2007 at 09:30

It would be nice if glucose would work to produce a high yield of crystalline picramate as well as giving a positive color test , indicating that some of that dyestuff has been produced . It may work to produce practical yields in the same way as does vitamin C , or it may not work that efficiently . That is an experiment which should also be done , since if it does work efficiently it would be the simplest and most economical method . I have continued to study what is reported concerning the polysulfide method in an effort to refine it , based upon the increased information gleaned from the few references which are relevant .

According to the Thiokol patent US2796325 ( attached below )

The mixture of NaOH solution or solid NaOH and Sulfur
follows two principal reaction routes which are dependant
upon the concentration of the NaOH and temperature .

for lower concentrations of NaOH < 30% and temperature < 110C

10 S + 6 NaOH ------> 2 Na2S4 + Na2S2O3 + 3 H2O

for higher concentrations of NaOH > 35% and reaction at > 100C to < 320C

10 S + 6 NaOH ------> Na2S4 + Na2S5 + Na2SO3 + 3 H2O

According to US1068769 ( attached above ) which describes a dry method preparation using " substantially equal proportions " , a mixed product results having byproducts which indicate that *both* the above reactions have taken place , and on a molar basis that nearly equal amounts of thiosulfate byproduct are produced , concurrently or subsequently to the sulfite byproduct . As a result of these byproducts , 27% of the NaOH and 12% of the Sulfur
used for the reaction wished to produce the polysulfide(s) is diverted to the formation of these byproducts . This appears to be an unavoidable loss which is necessary to the synthesis and inherent to the nature of the reaction .

Therefore , it would seem that an implied strategy for preparation of the polysulfide reagent should be to first make the mixed higher polysulfides , according to the dry method , using a 27% additional amount of NaOH and a 12% additional amount of sulfur to " makeup " for the amounts which will form byproduct thiosulfate and sulfite , instead of Na2S4 which will be the principal or average sulfur ranking 4 polysulfide product . The target amount of reducing sulfur compounds as product will contain 2.3 gram atoms of sulfur as S1 , or a slight amount more if desired , for each mole of nitroaromatic to be reduced .

The highest yields reported for the Zinin reduction are using both S2 and S1 ranking reducing sulfur compounds of sodium . See US1878950 for an example using an S2 ranked polysulfide reagent in the reduction of dinitrobenzne to nitroaniline . See the Hodgson and Ward 1945 JCS article attached to my preceding post for an S1 example more specific to producing sodium picramate from sodium picrate . Both of these high yield syntheses , using Na2S2 and NaSH respectively , use 2.3 gram moles of combined sulfur based on S1 , per mole of nitroaromatic compound , the highest yield for picramate using NaSH , which is derived from Na2S and NaHCO3 in aqueous solution .

To the initial product of higher polysulfides would then be added more NaOH sufficient to reduce its sulfur ranking to 1 , the compound Na2S . To this Na2S would then be added an equimolar amount of NaHCO3 to form the reducing reagent in aqueous solution . It would be expected that the initial melt would be very dark red colored due to the presence of higher sulfides such as Na2S5 particularly and also Na2S3 in substantial amounts in the mixture , but the mixture should lighten in color as the reaction proceeds with time and subsequent alkali additions intended to lower the sulfur ranking to S1 as the principal end product to be used as the reducing reagent .

The picric acid is dissolved in methanol , 25 grams in 250ml , at 55C , and neutralized to sodium picrate with 4.36 grams NaOH . The reducing reagent amounting to .25 mole of NaSH in 100 ml H2O is added gradually with stirring to the methanol solution of sodium picrate over 10 to 15 minutes
at 55 to 60 C . The mixture is cooled to 10C and diluted with 375 ml H2O , the sodium picramate filtered and washed with cold salt water . Yield reported is 96% when the reducing reagent is made up from pure Na2S and NaHCO3 . The yield should be high and hopefully close to that 96% , even when using this more improvised reagent containing its indigenous impurity of thiosulfate and sulfite originating from its preparation . These impurities shouldn't interfere
with the reduction and the expectation is that their presence will cause no problem , particularly as regards the thiosulfate , since it is a byproduct of the reduction anyway and is going to be present as such in the spent reaction mixture .

Though the ratio of 2.3 gram atoms S1 ranked reducing sulfur compound per mole of nitroaromatic is reported to give highest yield ....this is a minimum , and it does not hurt to use slightly more , so bearing that in mind as well as allowing for some possible incompleteness of reaction for
the improvised polysulfide reagent , I am increasing 10% beyond that theoretical to 2.52 to 1 , also because it is convenient in the measuring of exactly 10 grams of sulfur from which the composition will be made .

Based on these informations I can propose the following as a valid experimental for the improvised polysulfide reagent possibly having an effectiveness of the .25 mole of NaSH reagent used as described above .

Experimental :

Xylene could be useful for providing a vapor blanket to protect this reaction mixture from excessive exposure to air . Perhaps 20 - 30 ml would be fine for this purpose .
It would likely be best not to add the xylene in the greater part until after all the NaOH has been added , because the initial exotherm and the reaction benefits from a
temperature allowed to rise well above the bp of xylene , which if present in too great an amount would limit the temperature of reaction in the early couple of minutes where the exotherm should be allowed to proceed unhindered .

10 grams of flowers of sulfur are thoroughly mixed dry with 7.6 grams NaOH , the reaction initiated with a few drops of water and the exotherm maintained by additional minimum dilution ( 10ml H2O ) and supplemental heating , in the absence of air . The mixture is kept hot and liquid for 20 minutes , a further portion of 22.6 grams NaOH in 20ml H2O is gradually added . The mixture is kept hot for an additional 30 minutes . And then 13 grams of NaHCO3 in 100ml hot H2O is added , followed by 10 grams additional solid NaHCO3 , the mixture is stirred and heated an additional 10 minutes , then allowed to cool , keeping from exposure to air .

[Edited on 30-1-2007 by Rosco Bodine]

Attachment: US2796325 NaOH or Ca(OH)2 + Sulfur Polysulfide and Sulfite Manufacture.pdf (276kB)
This file has been downloaded 1741 times


further information on Na2S

Rosco Bodine - 31-1-2007 at 23:22

If it should prove unsuccessfull concerning my hopeful
" one pot " strategy for the formation first of a higher polysulfide Na2S4 , and then by adding alkali attempting to lower it to Na2S by further reaction .......there is an alternative method which can be used to produce and
isolate the Na2S .

This method is a bit more demanding on equipment ,
as I would expect that teflon or inconel would be needed
to resist the 50% NaOH at 140-150C used for the reaction ,
which would probably be more than labglass will withstand .

Anyway this patent is very similar to the Thiokol patent
US2796325 posted earlier , but it discloses much more specific details with regards to the conditions required
for producing *not* a polysulfide but rather the conditions for producing the monosulfide
which is the thing desired . In spite of the more demanding
conditions for the reaction ....this is actually the most pertinent reference to be found so far describing the convenient synthesis of Na2S in pure crystalline form .

[Edited on 1-2-2007 by Rosco Bodine]

Attachment: US2705187 Sodium Monosulfide from alkali and sulfur.pdf (613kB)
This file has been downloaded 1337 times


Sickman - 3-2-2007 at 21:48

Rosco,

Thank you for posting your research findings on methods of preparing sodium sulfide for the reduction of picric acid. It is encouraging that these methods can open a greater avenue for furthering research on the production and improvement of such picramic derivatives as DDNP.

I'm curious as to wether or not your renewed research in this area signifies that you are hopeful that DDNP can be produced in a form and improved in a fashion that will allow it's use as an "unequivicol", outstanding, primary explosive that we can all be proud of and be able to say that it is "absolutely reliable and useful as an initiator of secondary explosives in a firing train".

The great majority of the literature seemingly holds up DDNP in a place as high and note worthy as lead azide and mercury fuminate. By way of some of your postings in the thread "DDNP" it appears that your own conclusions about DDNP, at least in the form(s) that you were working with, indicate that you think the literature overvalues and makes more of DDNP than DDNP really has to offer as an initiator of secondary explosives. So do you think it can be managed to produce DDNP in a form (density) and in a fashion (unequivicality) that will rightly equate it with lead azide and mercury fuminate as a true and undeniably reliable, initiator of secondary explosives? Or does DDNP's value lie more in some other application than as an initiator?

I think the second possible method you suggested for the production of sodium monosulfide looks to have very interesting potential. Your concern for the glassware's corruption by hot, concentrated sodium hydroxide is understandable. I'm thinking that the glass would certainly be badly frosted if not completely cracked and destroyed. Because of this I think that the use of a steel, stainless steel, or even a copper vessel could be used with excellent results in this procedure. The only disadvantage of using vessels of these materials is that the visual observation of the reaction is impaired by their not being transparent.

Rosco Bodine - 4-2-2007 at 05:23

Quote:
Originally posted by Sickman
Rosco,

Thank you for posting your research findings on methods of preparing sodium sulfide for the reduction of picric acid. It is encouraging that these methods can open a greater avenue for furthering research on the production and improvement of such picramic derivatives as DDNP.


Yes it was clear early on that for any usefulness to be realized concerning DDNP ,
that two things would need to be optimized , the preparation of precursors , and the preparation of the DDNP from them in a crystalline form of increased density .

I am still looking at the sodium monosulfide synthesis ,
which needs some work yet . It appears that the mixing
of the sodium hydroxide and sulfur as solids is certainly
on the right track . But it looks like that for the monosulfide to form
as the prinicipal product requires an excess of theory
for the NaOH , as little dilution and/or byproduct water as
is needed to maintain the melt , as high a temperature as is
manageable to drive the reaction , and for as long a time
as is convenient ......all while minimizing exposure to air .
After that reaction is deemed complete and diluted then
the excess alkalinity has to be adjusted with sodium bicarbonate .
I believe the hot phase of this reaction
would best be done under a high boiling solvent , perhaps
kerosene or white mineral oil for example .

Quote:

I'm curious as to wether or not your renewed research in this area signifies that you are hopeful that DDNP can be produced in a form and improved in a fashion that will allow it's use as an "unequivicol", outstanding, primary explosive that we can all be proud of and be able to say that it is "absolutely reliable and useful as an initiator of secondary explosives in a firing train".


No , I have no such confidence in DDNP even optimized
being able to compare favorably with azides , but it may be
a still usable if marginal initiator , and some of its derivatives
or composites with other materials could have usefulness .

Quote:

The great majority of the literature seemingly holds up DDNP in a place as high and note worthy as lead azide and mercury fuminate.


Yeah the literature is way wrong in its favorable comparisons about DDNP
just the same as it is wrong about HMTD , both will work as initiators ....but they both are very minimal compared to lead azide or azo-clathrates , or other medium to high performance initiators .

Quote:

By way of some of your postings in the thread "DDNP" it appears that your own conclusions about DDNP, at least in the form(s) that you were working with, indicate that you think the literature overvalues and makes more of DDNP than DDNP really has to offer as an initiator of secondary explosives. So do you think it can be managed to produce DDNP in a form (density) and in a fashion (unequivicality) that will rightly equate it with lead azide and mercury fuminate as a true and undeniably reliable, initiator of secondary explosives? Or does DDNP's value lie more in some other application than as an initiator?


Oh it has value as an intitiator , but like I said it is more
comparable with HMTD in its power .....and no it will never
be an unequivocal primary initiatior like lead azide .....
but is a DDT initiator like lead styphnate . Even lead styphnate is an initiator if you don't mind using three grams of it in a reenforced cap , just to get a gram of picric acid base charge going .....so you see it is the reasonable quantity minimum to surely do the job ,
which makes an initiator worthwhile . DDNP could do the job , but it would be more useful with the more sensitive base charges , where its impulse would be sufficient so that a more reasonable minimum quantity would be required .

Quote:

I think the second possible method you suggested for the production of sodium monosulfide looks to have very interesting potential. Your concern for the glassware's corruption by hot, concentrated sodium hydroxide is understandable. I'm thinking that the glass would certainly be badly frosted if not completely cracked and destroyed. Because of this I think that the use of a steel, stainless steel, or even a copper vessel could be used with excellent results in this procedure. The only disadvantage of using vessels of these materials is that the visual observation of the reaction is impaired by their not being transparent.


Yeah copper is exactly what I have been thinking about too ,
something like a small copper pot with a lid , deep enough
to put a layer of kerosene over the melt .

The molar ratio seems like it should be 8 or 9 NaOH to 3 S1 ,
perhaps even 10 to 3 , and run the reaction with supplemental heating
for at least 30 minutes , having it between perhaps 175C to 300C at the end ,
followed by a dilution and cooling to perhaps 150C when the NaHCO3 in an amount needed is added gradually to convert excess hydroxide to normal carbonate , and precipitate Na2S . I am studying what I can find about the solubilities and cosolubilities possible in such a system to try to guess the optimum dilution/s and filtration temperatures and sequence which should give the desired
Na2S from the unconventional mixture . If this can be done
reasonably well , then it will avoid the alternative of having
to use manganous or ferrous or zinc sulfate as a precipitant
of their insoluble monosulfides , as a precursor for an H2S
generation scheme to treat an NaOH solution and obtain
the product that way .

Reacting NaOH and sulfur does produce some of the active
reducing sulfur compounds desired , Na2S and Na2S2 are
both Zinin reagents ....but of course to get the yields of
picramic acid increased , the monosulfide is the desired product .
The minor problem is that the reaction mixture
is inclined to form a lot of higher polysulfides which are quite stable like Na2S4
....unless the reaction towards the lower sulfide is forced with excess alkali , high temperature , and reaction time , with the reactants in high concentration .
Trying to get these atoms to jump through the hoops and
sit on their appointed stools awaiting further commands ,
does require cracking the whip for this reaction :D

A bit more complicated , but technically superior

Rosco Bodine - 4-2-2007 at 17:55

The reaction dynamics involving the formation of Na2S
have been further reviewed and considered . I think I have
( finally ) devised the plan that should work best , a sequence which accommodates and exploits the natural tendencies of the reactions involved in order to minimize losses , and maximize the overall economy and Na2S yield for a labscale synthesis , while bringing the reaction mixture requirements to a milder reaction condition which shouldn't be destructive to labglass . But you don't get something for nothing , and handling a toxic H2S gas is unavoidable for this alternate method ....the advantages otherwise however should make the extra effort worthwhile .

So here's the plan . The reaction between NaOH and Sulfur
most easily , quickly , and efficiently forms Na2S4 polysulfide by the general method of the Thiokol patent , but modified with the Dry Method strategy for speeding the reaction with fairly high initial temperature and concentration , probably in
20 to 30 minutes the polysulfide reaction is pretty well complete . I still think that performing this reaction hot
and under a covering layer of kerosene or perhaps white mineral oil would be best .

Since the Na2S4 forms relatively easily in high yield , and without excessive alkali or other extreme conditions , then that is what we make . And we don't even try to isolate Na2S4 after formation , but simply dilute the completed reaction mixture enough to keep it from setting up on cooling .

The proportions which would seem a good starting point
are for 6 moles NaOH , 9.4 moles S ( as S1 ) .
A quick 100ml beaker reaction exotherm melt test concerning those proportions would be on a weight basis 8 grams NaOH and 10 grams sulfur .

It is not known for certain that this polysulfide is the fastest forming polysulfide or the one which goes furthest to completion soonest . The Thiokol patent is ambiguous about this , and only states that the polysulfides from a ranking of 2 to 5 form faster than the monosulfide , not which of the
higher polysulfides is fastest . So Na2S2 or Na2S3 or
some intermediate mixture may prove by experiments to be
optimum . The ease of mixing and the way the melt behaves
is of some importance also , so the ratio of NaOH to S may be
varied for physical reasons , to obtain a melt which forms smoothly . The quantity of NaOH could range upwards to 16 grams per 10 grams of sulfur . This is not critical but would only affect the time of reaction to complete , and the adjustment of stoichiometry being applied to the remainder of the reactions , subsequent to the formation of whatever
ranking of polysulfide proves best . In some of my preliminary melt tests I found an equimolar mixture of
NaOH with Sulfur gave a smooth forming melt . So this is the one area where some tweaking of proportions and experiments would still reveal what is the optimum ratio ,
all things being taken into account .

We generate H2S by acidifying the completed Na2S4 containing reaction mixture , by running it into a hot solution of sodium bisulfate or ammonium bisulfate , or dilute sulfuric acid . Three quarters of the "soluble sulfur" , the 3S "polysulfide" content of the Na2S4 polysulfide , those 3 sulfurs which are in excess of the one S chemically combined S as Na2S , are simply split off and precipitated as free sulfur , when the mixture is acidified to form H2S , but sulfur is cheap . If desired it can be settled out and filtered , recycled , but hardly worth the effort for a labscale process .

The H2S is bubbled into an NaOH solution where it is neutralized to form Na2S as the first product , and if gassing
is continued then NaHS is the resulting solution , which can be converted back to Na2S simply by adding an equimolar
amount of NaOH to again form the neutral salt . The completion point for the NaHS formation can be detected when blowthrough causes insoluble FeS to appear as a precipitate in a final scrubber bottle containing ferrous sulfate . When this occurs , an equal amount of NaOH
as was used to make the solution originally is added ,
and that reactor is now full of a hot solution of Na2S .

The end result of this method is pure Na2S crystals via
a process which although it is inefficient compared with
industrial methods ....is however manageable in a labglass
environment for a labscale method leading to a good yield
of the pure crystalline material desired , via a process
that is stoichiometrically predictable and should have a yield
estimated at 95% , perhaps better .

The use of tubing and stoppered bottles , anti-suckback
traps , and a final bubbler jug of NaOH or ferrous sulfate solution as a reactor half reaction completion point and blow through indicator , and final scrubber for any excess H2S which may slip through the reactor ....would be required .

I would probably put a small forward flow of hydrogen ,
or perhaps even air through the system ....to nullify
any suck-back problems . Using small bore tubing greatly eliminates suck-back problems anyway for these sorts or
gas reactions .

This method involves no really extreme conditions or equipment requirements ,
however ...
H2S is a highly toxic and dangerous gas so that is a disadvantage and it would require careful handling ....
but otherwise this strategy is straightforward and
absolutely should work .

[Edited on 5-2-2007 by Rosco Bodine]

nitro-genes - 21-2-2009 at 14:24

Sorry for bringing up this old thread. :)

Recently I tried the reduction of picric to picramic acid using polysulfide. The polysulfide was produced by the earlier mentioned dry melt of NaOH and S, kept at 150 deg. C.for half an hour after the initial exotherm in an airtight container.

The melt was dissolved in about 8 times it's volume of water and added to a near saturated solution of sodium picrate, produced by neutralizing double recrystalized Picric Acid with PA grade NaOH. The mixture was allowed to stand at room temperature for about 48 hours. Red crystals of sodium picramate collected at the bottom of the beaker. The crystals were washed thouroughly using ice water and dried. I noticed a distinct sulfur smell though, so I dissolved the crystals again in the least amount of water after which 10% HCl was added slowly to precipitate the pure picramic acid.

Now, there were several things that were unexpected:

1 The pure picramic acid collected as a fine amorphous BROWN powder, while PATR mentions a distinct RED color. Is this simply because of it beeing amourphous? What is the colour of picramic acid from others experiences?

2 The sulfur smell still is quite noticably

In the article: "The Preferential Reduction of Nitro-groups, etc. Pavt III, J[1]. Chem. Soc., 1945, 663 - 665" They mention brown dyes, called " sulfur dyes", as the by product of the partial reduction of Picric to Picramic acid using the sodium carbonate/sulfide process. Does anyone know what these sulfur dyes could be and which condition favour there formation? Could this relate tot the persistent sulfur smell?

Thanks...

additional methods of possible interest

Rosco Bodine - 22-2-2009 at 00:18

(1)Here is another variant on the method using H2S which I was proposing in the previous post.
See attached file.

The purification of the crude picramic acid for removal of
sulfur would be avoided entirely by a different reduction method. Ascorbic acid (sodium ascorbate)
works as a reducing agent, and reducing sugars in alkaline condition and ferrous sulfate or possible better ferrous ammonium sulfate may also work as reducing agents, leading to a more easily purified product.

(2)Here is yet another reported method which may be done using powdered zinc to reduce ammonium picrate in H2O solution made basic with excess ammonia. I speculate that perhaps if some ammonium nitrate is present that this may improve the reaction via formation of nascent ammonia, but this would have to be tested by experiment. At the end of the reduction using zinc, I would expect that the reaction mixture would have to be acidified and digested with dilute HCl or H2SO4 to decompose the zinc picramate and precipitate and isolate the free picramic acid, leaving the soluble zinc salt and other byproducts as filterable solution. The original French pharmaceutical journal article probably has more detail on this.



[Edited on 22-2-2009 by Rosco Bodine]

Attachment: picramic acid preparation via H2S.pdf (180kB)
This file has been downloaded 1266 times


Axt - 22-2-2009 at 07:05

Just a couple interesting abstracts on the ascorbic acid reduction.

<b>Colorimetric determination of ascorbic acid</b>. Di Bacco, Giulio. Bollettino Chimico Farmaceutico (1953), 92 115-19.

Abstract

Dissolve 0.235 g. picramic acid in 400 cc. H2O and 25 cc. 2% NaOH. Heat and bring the cooled soln. to a vol. of 1 l. Mix 5 cc. of a soln. of ascorbic acid contg. 1 mg. per cc. with 3 cc. 0.1% picric acid soln. and 2 cc. 2% NaOH soln. In another tube mix 8 cc. of the picramic acid soln. with 1.8 cc. 2% NaOH soln. and 0.2 cc. H2O. Heat both tubes 3 min. at 100, cool, and compare colorimetrically. Five mg. of ascorbic acid reduces picric acid to form 1.884 mg. picramic acid which is exactly the quantity used for comparison

<b>Ascorbic acid: a Jaffe interference</b>. Viraraghavan, Saroja. Regina, SK, Can. Bulletin of the Chemical Society of Japan (1992), 65(4), 1101-8.

Abstract

The effects of ascorbate, the interference of the Jaffe reaction was individually studied by polarog., spectrophotometry, and TLC. Picramic acid formed in all ascorbate:28.4 mmol dm-3 picrate test solns. which explained the obsd. pos. interference of ascorbic acid. No fluorescent product was formed in ascorbate:picrate test solns. The reactivity of ascorbate:picrate test solns. confirmed that ascorbate was a powerful reducing agent. 2-Furaldeyde which has been listed as one of the degrdn. products of ascorbic acid, is not identified under the exptl. conditions.

[Edited on 23-2-2009 by Axt]

amalgamated sheet zinc may possibly work

Rosco Bodine - 22-2-2009 at 10:12

I am wondering if a variation upon the powdered zinc reduction method may work as well using amalgamated zinc sheet scavenged from an ordinary carbon zinc battery and left in a split cylinder form standing in a beaker.

For an expedient method I was thinking this could be useful if it works and if the amalgamated zinc isn't too active a reducing agent, which it may not be at mild temperature. The idea would be to first clean and lightly etch the sheet zinc using HCl and then amalgamate using HgCl2. The amalgamated sheet zinc is immersed in a beaker containing a stirred solution of sodium picrate and ammonium nitrate solution is added dropwise to accomplish the reduction.

I am proposing to use sodium picrate instead of ammonium picrate because of the much better solubility. Magnesium picrate may also work.

After the reduction is complete, the product will be a picramate salt or mixed picramate salts, sodium, zinc, ammonium, ect. and the spent reduction mixture will need to be acidified with HCl and digested to solubilize the cations as their chlorides and precipitate the little soluble free picramic acid which may be filtered.

With regards to the sulfide reduction schemes which have been discussed earlier there is an attached article which should be posted here with this thread. It has also been posted in another thread in answer to a problem reported using thioacetamide in an unsuccessful attempted reduction
of sodium picrate to sodium picramate. Evidently the reduction is pH sensitive and requires an alkaline reaction condition, because the actual reduction occurs via an alkaline sulfide intermediate formed in situ via reaction with H2S when H2S is used as the presumptive reductant.

[Edited on 22-2-2009 by Rosco Bodine]

Attachment: American_Journal_of_Science 1861 pg188.pdf (145kB)
This file has been downloaded 1157 times


nitro-genes - 23-2-2009 at 15:14

The brown sludge, presumed to be picramic acid, was diazotized using KNO2/HCl as described in literature, and yields some even darker brown stuff that appears to be DDNP. However, the sulfur smell is still quite noticable, and I have come to believe that this is not due to additional sulfides/sulfur or thiosulfate present as a left over impurity.

I also did a fast mg-scale experiment using ascrobic acid and some left over picric acid, to determine if the reduction to picramic works this way. More than 15 minutes at room temperature after the addition of ascorbate gave virtually no colour change, while boiling for a couple of minutes produced the same red colour as in the Zinin-like polysulfide reduction of PA . Upon addition of the polysulfide reagent however, the colour change is instantly and might indicate that the ascorbate reduction may actually be more selective. I have no idea however what the colour is of the products formed in the case of further reduction of additional nitrogroups.

More off topic:

The idea was to make DDNP using only common, store-bought stuff with some help of others their experiences and write ups, both here and on a Dutch EM-related board, called Pyroforum.nl.

Since NaNO2 was the only chemical difficult to produce for the synthesis of DDNP I actually found a nice way to produce relatively pure NaNO2 from common materials. It has been described in literature, though I have never seen actual descriptions and yields from this process on any discussionboards. I had tried several other processes, such as the formation of NaNO2 by absorbing 1:1 mixtures of NO and NO2 (N2O3) in NaOH, though NaNO3 is a major by product, presumably because of an excess NO2.

Instead I used the Pb/KNO3 or NaNO3 process:

Outside and wearing gloves, 250 grams of lead (20% excess) was melted in a stainless steel vessel after which 100 grams of KNO3 was added at once. The mixture was stirred until all the KNO3 had melted and formed a clear layer floating on top of the molten lead. Some yellow/brown PbO started immediately to form, however, upon prolonged heating there was little to no further formation of PbO.
I decided to heat the mixture stronger and within about 10 minutes a strong exothermic reaction became evident. In a beautifully controlled manner and without any gas formation, the entire mixture became red hot. The mixture was well stirrable and this was done so for another couple of minutes to ensure reaction of all the KNO3 present. (The lead has a tendancy to sink immidiately to the bottom again)
It is important to keep stirring to the point of solidification, since it makes extracting the KNO2 much easier! The mixture was ground together with several additions of water, until all the PbO was present as a fine powder at the bottom and filtered to remove any PbO. The light yellow filtrate was then boiled to dryness (takes long time, due to hygroscopicity) and yielded about 65-70 grams of KNO2.

Potassium plumbate is said to be one of the by products of the reaction, however addition of H2SO4 to the mother liquor prior to evaporation yielded no visible precipitate of PbSO4 or clouding of the solution.

Upon addition of 5% HCl to the solution produces NO which is quickly further oxidized to the red NO2 when it escapes from the solution.

[Edited on by nitro-genes]

Rosco Bodine - 26-2-2009 at 21:04

back on topic ....nitrites are a separate matter
and for that much other methods could be used for diazotization.... also another topic

I have been looking at the early references
concerning the preparation of picramic acid from which I may post more excerpts later. Excerpt from article attached



This author, Aime Girard, named the compound picramic acid,
which had earlier been called by Wohler "reduced carbazotic acid" and had been called by Berzelius "nitrohaematic acid".

It appears the reduction is most definitely a pH sensitive reaction as observed by many researchers. In an acidic reaction system free picric acid is reduced all the way to triaminophenol but in an alkaline reaction condition the reduction is incomplete and selective for only the one nitro group and a picramate is the product. Even nascent hydrogen such as from electrolysis or an amalgam should
be selective for the limited reduction desired, so long as the reaction condition is kept at a basic pH. Free ammonia
either added as NH4OH or liberated in situ via an ammonium salt and an alkali would seem to me to be an applicable strategy for this reduction, though I have not seen that specifically reported in the literature. It just seems to be a likely approach worth trying. A possible method here is using aluminum amalgam and perhaps some ammonium nitrate or sulfate used as a source for in situ ammonia reaction byproduct to keep the reaction mixture basic.

Ferrous sulfate , ferrous chloride, stannous chloride, cuprous chloride will effect the selective reduction ....again only in an alkaline reaction system , a reaction mixture kept to a basic pH. The stannous and cuprous salts only act when freshly precipitated by ammonia, so it would seem it is the nascent hydroxides which are the active reductant and this possibly also holds true for the ferrous compound.

Also according to Girard reportedly soluble picramate salts do not cause a precipitate with soluble iron salts so this may be a tool for purification, possibly accomplishing removal of the occluded free sulfur microscopic particles or soluble sulfide impurity which seem to be a persistant contaminant, via precipitation of the undesired sulfur values using ferrous sulfate solution to sequester the unwanted sulfur as a precipitated iron sulfide which may be filtered from the solution of soluble picramate.
The behavior with respect to salts of manganese is the same,
also cobalt and nickel.

Ferrous sulfate itself may be used as the reductant for the
soluble picrate originally, if the reduction is carried out under alkaline condition, 6 of the Ferrous Sulfates required for the
theoretical, in the same way as are 6 Sodium Ascorbates,
for the theoretical conversion of 1 mole of alkaline picrate to 1 mole of alkaline picramate. The basic salts would most often be the sodium or ammonium or some mixture of these, owing to the greater solubility making these convenient, but
other soluble salts may also work in a more diluted reaction system.

The residual sulfur contamination which is attendant to the polysulfide reduction could probably be minimized by very careful neutralization. There is likely an optimum pH to which the filtered and redissolved sodium picramate can be adjusted with HCl or H2SO4 which will decompose any residual sodium sulfide or polysulfide and the H2S driven away by boiling, and the free sulfur settled and or filtered
from the warm solution of sodium picramate, prior to further
addition of acid to precipitate the free picramic acid.

One reference to an industrial scale production reported that
the reduction was run at a pH kept *neutral* by a gradual
addition of acid and the reaction temperature regulated at 80C, and that the sodium picramate precipitated from this
Na2S reduction of an ammonium picramate slurry, precipitated as the monohydrate sodium picramate. If that report is accurate, then a buffered reaction may also be feasible but what is the target pH desired I am not quite sure, and I am skeptical it is actually neutral pH which was being the regulation point there in that one reference.
Anyway it is established it can't be acidic so there is possibly
a range there close to neutral which is workable, erring on the basic range is what the more numerous references would indicate. Also a cosolvent system using methanol
and H2O for the reduction can increase yields by 10% or so
from the mid 80% to the mid 90% range.

[Edited on 27-2-2009 by Rosco Bodine]

Attachment: Pages from The Chemical Gazette, Or, Journal of Practical Chemistry, in All Its Applications to Pharmacy, Arts, and Manu (179kB)
This file has been downloaded 1332 times


Rosco Bodine - 27-2-2009 at 00:32

Here's an excerpt from the Egerer J. Biol. Chem. article linked five posts above, which describes H2S in reaction with an ammoniacal solution of ammonium picrate, forming in situ the ammonium sulfide which acts as the actual reductant. Note the free sulfur byproduct mentioned as a contaminant using this even more refined alkaline sulfide reduction method. So it would seem that given this problematic contamination with free sulfur, that alternate methods of reduction which do not produce this contaminant as a byproduct are more interesting. This brings the entire matter full circle back to the ferrous sulfate reduction, or possibly to alternative reduction schemes like powdered zinc or amalgamated zinc or aluminum, to be considered as advancements over the alkaline sulfide reduction methods. Again, here the ferrous sulfate may have a value in either case, for purification if not better for the entrie reduction.



Attached is a more extensive article by Girard

[Edited on 27-2-2009 by Rosco Bodine]

Attachment: Pages from The Chemist pg348.pdf (314kB)
This file has been downloaded 1110 times


nitro-genes - 17-8-2010 at 07:26

In my experience, it is very difficult to get completely rid of the sulfur/polysulfides while recrystallizing picramic acid. United States Patent 6268536 describes toluene extraction of picric acid from nitration mixtures.

Any idea what the solubility of picramic acid is in toluene, or maybe DCM? Thinking OTC paintstrippers and one step purification...

else the same principle could more or less apply here as well. Couldn't find the answer in PATR, Urbanski or Google... :)

Thanks

[Edited on 17-8-2010 by nitro-genes]

Rosco Bodine - 17-8-2010 at 12:42

Picramic acid is soluble in alcohol and probably in acetone.
Toluene might be a poor choice because sulfur is very soluble
in toluene. Sulfur and hot toluene is described here by garage chemist. I think later he became an ascended being:D
http://www.sciencemadness.org/talk/viewthread.php?tid=3902#p...

This is an area of experimentation which I intend to revisit, and explore uses of reducing agents other than polysulfides. I have read in many different isolated references that many different reducing agents are effective in producing picramic acid via the reduction of picric acid, but more correctly stated it is not the reduction of picric acid itself at all, but reduction of the one of picric acid nitro groups on the picric acid while the picric acid is associated as a picrate salt in an alkaline medium. Therefore high pH is the reaction condition which determines that the reduction will be limited to the one nitro group of a picrate, as opposed to the reduction of picric acid itself which would lead to triaminophenol as the product
of a reduction carried out at low pH upon picric acid itself. So any reducing agent which functions in an alkaline condition should produce picramic acid, or more correctly a picramate salt as the product of the inherently milder and limited reduction as occurs for reduction of a picrate salt at high pH.

The operative issue then is one of clarifying the semantics that is confusing, recognizing that what is being done is not reduction of picric acid to picramic acid as that mechanism does not occur. What may occur and what we seek is reduction of a picrate salt, typically sodium picrate, to produce sodium picramate.

Many reducing agents should work for production of the desired picramate so long as the required pH range for the reduction of picrate to picramate exists in the reaction mixture. Ferrous sulfate, dextrose, ascorbic acid, amalgamated zinc or aluminum, probably even iron filings could be used.

Carefully done synthesis of DDNP under very specific reaction conditions which improve the crystalline size and bulk density of the product would probably evidence better performance for the DDNP than is gotten generally for tests of DDNP which is of lesser purity and lower density. Quality control can have great bearing on the product test results, particularly for materials that are sensitive to small variables.
Where the margin of acceptable performance is small for a material which is only useful in a particular form and quality, the quality control has to be stringent, and I believe this probably applies to DDNP.


[Edited on 17-8-2010 by Rosco Bodine]

Ammonium sulphide

The WiZard is In - 18-8-2010 at 13:42

Dinitroamidophenol is produced by treating an alcoholic solution
of picric acid with ammonium sulphide. The sol. is evaporated on
a water bath and the residual ammonium picrate decomposed
with nitric acid.... This substance was formerly used as a brown
dye.

Capt. Colver, &c.

Rosco Bodine - 18-8-2010 at 17:49

It seems likely that thiourea would also work, if sulfur being avoided for the reduction is a non-issue.

http://www.sciencemadness.org/talk/viewthread.php?tid=1255

nitro-genes - 24-8-2010 at 15:06

Regarding glucose (dextrose)...

J Clin Chem Clin Biochem. 1990 Feb;28(2):95-105.
Effect of glucose upon alkaline picrate: a Jaffé interference.

This abstract looked promising, although it seems less selective than either HS or sodium ascorbate, especially at higher glucose/TNP ratios, where the reduction is carried further to produce 2,6-diamino-4-nitrophenol to some extend. They also mention other products formed, as well as unreacted picrate, so I have a feeling that optimizing this one to consistently produce picramic acid in high yield may be troublesome. Still worth a try though...(some day)




Rosco Bodine - 9-10-2010 at 09:51

Formaldehyde is another possibly useful reducing agent since it does work for some reactions in an alkaline reaction mixture, similarly as the reaction condition
for Vitamin C and reducing sugars. If workable this would be a very easy and cheap route. Paraformaldehyde is depolymerized by warming with sodium hydroxide resulting in a basic solution of formaldehyde and this could be added to a warm solution of sodium picrate. Hopefully the formaldehyde would be oxidized to formic acid, which would remain in solution as sodium formate, and the sodium picramate would crystallize out.

A possible complication that could interfere with the desired reaction would be the potential further reaction of formaldehyde in some undesired way. Further reaction could occur simultaneously or subsequently with the desired reduction. Interesting perhaps, as this further reaction, if it occurs, might itself also lead to a useful but different product.

[Edited on 9-10-2010 by Rosco Bodine]

A valdDNP synthesis?

prometheus1970 - 21-1-2011 at 18:25

I recently found this synth for DDNP can anyone tell me if it's viable or dookie?:

MANUFACTURE:
1. Mix in a beaker 90 ml warm water and 1.5 grams of sodium hydroxide until all
NaOH is dissolved.
2. Stir in carefully 9 grams of picric acid in the above solution. Name it solution 1.
3. In the second beaker fill 300 ml water. Stir in 7.5 grams of sulfur and 7.5 g. of
NaOH.
Boil this solution over a heating source.
After a few minutes of boiling, the solution turns red.
Allow to cool. Name it solution 2.
4. Add solution 2, under stirring, in three portions to soln. 1 and allow to cool.
5. Filter the soln. through coffee filter.
Small red crystals should form. Discard the liquid.
6. These red crystals are added to 180 ml of boiling water.
Filter hot. Discard the crystals collect in filter paper, and name the liquid soln. 3.
7. Slowly and drop by drop add conc. sulfuric acid to soln. 3 until the soln. turns
orange-brown.
8. Add to the orange-brown soln. 7.5 grams of sulfuric acid.
9. In 2nd beaker dissolve 5.4 grams of potassium or sodium nitrite in 240 ml of water.
Name it soln. 4.
10. Soln. 4 is added in one portion to soln. 3 under well stirring.
11. Let mixture sit for ca 10 minutes.
Filter the now brown solution (pure DDNP) through a paper.
The crystals left are washed with 60 ml water.
Let dry for 24 hours.
DDNP is best stored with 25% water. Load moist in detonator

Rosco Bodine - 22-1-2011 at 00:30

Pleeeeease ......not that old improvised munitions blackbook bullcrap again.

Ultra pure ghetto class Dookie is what that would be. Do some reading in this forum for awhile and figure out that a fairly comprehensive review of literature and a fairly extensive amount of experimentation has already been done that is a whole lot blacker galactic blackbird than any black book starling you may run across conspicuously perched on a downtown grid line. Country boys are us.

prometheus1970 - 22-1-2011 at 07:53

Thanks, I suspected as much. Every other DDNP synth I've found requires first synthing picramic acid from picric, then combining the two, etc. I got all starry-eyed when I thought maybe I could skip that extra stuff, but it looks like DDNP will remain a synth that is probably out of my reach.

Rosco Bodine - 22-1-2011 at 08:51

Shouldn't be too difficult. Now we know that the picrate salt is what is reduced
under basic conditions to a picramate, so any one of many reduction schemes would probably work to produce the picramate precursor.
Ferrous sulfate or ascorbic acid or zinc or iron are known reductants, and many other reductants should work as well. Purification of the picramate via acid conversion to picramic acid is probably a good idea. Then it should be easy to use the improved crystal DDNP synthesis to get a useful dense form of the pure DDNP.

Boiling a reducing agent exposes it to atmospheric oxidation and the reducing property is thereby lost. Also the method for producing a dense pure form of DDNP is not described by that ghetto method. What is gotten following that
oversimplified method is a very impure and unuseful low density DDNP that
either won't work well or won't work at all as an initiator. That field expedient
method is at least twenty years old and it doesn't work to produce a DDNP having the desired properties.

prometheus1970 - 23-1-2011 at 07:44

I just set up an account at Sigma Aldrich so that I can buy picric acid directly. That is, assuming they will ship to a residence. Maybe they'll have picramic acid too. Although ordering both picric and picramic acid may well throw up some red flags...

hissingnoise - 23-1-2011 at 08:10

Quote:
I just set up an account at Sigma Aldrich so that I can buy picric acid directly. That is, assuming they will ship to a residence.

If you can prove you have a licensed bio-lab - sure!



prometheus1970 - 23-1-2011 at 15:39

Once again there go my hopes dashed upon the rocks of reality that await hungrily below the lofty cliffs of my naive optimism.

nitro-genes - 23-1-2011 at 16:51

Sorry to say, but I have the feeling that nothing about the synthesis of DDNP is easy when OTC materials are used. I think finding an OTC way of producing pure sodium (hydro) sulfate is indeed the way to go! :)

hissingnoise - 24-1-2011 at 02:48

Quote: Originally posted by prometheus1970  
. . . my naive optimism.

Try Aldrich anyway - you might get lucky if you put a good cover-story together.
Tell them you're doing bacteriological studies and need a saturated picric acid solution.


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