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Author: Subject: Picric acid: different instructions
Hennig Brand
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[*] posted on 31-7-2010 at 16:10


Thanks alot for the help. I am going to clean up some Lead Nitrate tommorrow maybe. I'll get back with results, of what I hope will be a Picrate that looks like Quicksilver's.

Rosco, if I am getting a fairly high yeild from a TNP from ASA synth, and recrystallizing, it would have to be quite pure, wouldn't it?

[Edited on 1-8-2010 by Hennig Brand]
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Rosco Bodine
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[*] posted on 31-7-2010 at 16:54


That is a good question. A lot of folks who think they have a good handle on picric acid may not have exactly what they think they have. It isn't totally foolproof, so some attention to detail is important there. The color of the product is telling for the purity of picric acid. If you go back to page six of this thread and look at the photo documentary that ordenblitz did, you can see how light colored
the still very acidic crude picric acid is on the first dilution, it is actually virtually white or very nearly white coming out of the first diluted nitration mixture, and that is a very good sign of purity, and so is the absence of "red goo" when doing a subsequent concentration by boiling down the residual solution from the first recrystallization for a second or even third crop of crystals. If you have a good clean high yield synthesis and clean crystallizations from that, then you are at close to 100% purity by color, melting point, titration, and other tests. If you have something less pure then it may be okay and it may not be okay depending on how demanding is the use, and I'm not sure what the range of tolerance is there, for syntheses or other uses. For synthesis it is probably a lesson you are getting that purity matters, and other variables too. But you are on the right track to be looking at the components with suspicion when a reaction that should work doesn't work for some reason. It isn't just jinxed for bad luck, but there is a real physical or chemical parameter that is out of spec, that is preventing the expected result.

[Edited on 1-8-2010 by Rosco Bodine]
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[*] posted on 1-8-2010 at 06:41


For what it's worth I have learned a few lessons regarding successful synthesis in general - the variables that I needed to pay attention to:
I learned to "tighten up" on the addition of weights and their timing of addition, the temperature of the synthesis, the ph (where appropriate), I bought various stir-bars because on occasion the density of the materials changes and a heavier stir-bar allowed the continual mixing & exposure to continue without being "bogged down" by increased density or other factors to maintain exposure to my nitration acid (or other situations where the mixing was an influence).

I used a wrist-watch and simple volumetric devices to do my best to not let additions range out of control. If a sep-funnel was used: I tested it first: not while I was actively nitrating, if a dry powdered product was used I did my best to be consistent in those additions or adjust as necessary, striving for consistency in those additions. A digital thermometer (or quality glass one) was situated so that I knew what my temp was with the best accuracy I could maintain. If combinations or a pre-mix of chemicals needed to be available, I'd set up those in clearly labeled beakers or flasks away from the main activity - so I was not mixing and watching temp, etc at the same moment.

If I had to use an out-door setup (because of fumes) I kept as much UV away from my work as I could. A poorly working fume hood is worse than no hood, because if you KNOW you don't have fume safety you can take safety measure. But if the hood doesn't work well, heavy fumes WILL bite you. Some synthesis are "fume volume heavy" & it's important to account for that!
Before I would begin a lab, I took a moment & thought through what was going to take place and assembled my goodies, so that I would not be searching for an item or leaving my work area. I keep safety stuff on hand but also had both a notebook and the pre-defined synthesis printed out so that I didn't have to guess & I could record an anomaly. Occasionally the notes became very import to repeating a synthesis successfully as I would find a significant variable that had to be accounted for.


The bottom line, was that I made sure I was in control of the procedure: taking myself from "imitating a recipe" to understanding the chemistry & preforming a synthesis. The formula itself began to not only make sense but became a larger scale map of the activity. The greater my control of the procedure I had, the greater I could define the formula.




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[*] posted on 1-8-2010 at 10:48


Thanks for all the good advice.
No real joy again though in my case. My yeild is up to 8g (actually 4, as I did a half scale batch). I think I fixed my Lead Nitrate problem though. I made a hot saturated solution of Lead Nitrate, cooled, then strained out the large crystals, and dried them well with very low heat over 2 hours. I used a scale that was accurate to 0.01g, and was very careful with my weighing of the reactants. I have a fairly good yeild of very energetic material, but it is still dark orangey yellow, not the rust colored stuff Quicksilver had.

Even though my yeild of TNP last time was very close proportionately to what Ordenblitz got back on page 6 of this thread, I still think I have lower nitro phenols or other contaminants in considerable quantity in my TNP.
I think I need to be a little more careful to get complete nitration in the final stage with heating. Mechanical stirring and longer final stage nitration at 110C+ would probably help.

To me it is starting to look like Basic Lead Picrate might be a good way to test purity of TNP. Of course there could still be something I am missing, that is wrong.

I will spare you another picture. It is just a little darker orange than last time.


[Edited on 1-8-2010 by Hennig Brand]
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[*] posted on 1-8-2010 at 11:30


Because it is a powerful dye even at 1 ppm, and some of the potential impurities are also strong dyes, it wouldn't take much impurity at all to cause a color shift.
Really it is the yield being off that is the bigger indicator of a possible problem, when that is taken together with a color shift it is more conclusive with two parameters raising suspicion then being doubly suspicious, as one is bad enough.

It is much easier for the neutralization on something like this to make up a larger sample of a standard solution of NaOH using a density chart and confirm by titration and an indicator if you want to make twice sure of the molar strength,
and then to measure out the volume needed using a buret or a syringe, or weighing the needed amount of verified strength of solution. With a hygrosocopic solid like NaOH and working with small quantities, it is about impossible to be accurate by weighing out a small amount of solid having a moisture content growing by the second as you are trying to weigh it.

You can do the stoichiometry and get the actual required amounts a bit closer
to theoretical than is given by the stated proportions of the Friederich patent.
It may be that you are simply not allowing enough time / temperature / agitation for the material to transition forms, to "develop" .....and it indeed does go through a gradual transition, so you may be picking your plum before it is ripe, robbing the cradle, ect. :P


[Edited on 1-8-2010 by Rosco Bodine]
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[*] posted on 1-8-2010 at 13:12


I shouldn't maybe be admitting to this, but I think it does illustrate something(maybe). The first couple of times I made(tried) Basic LP I literally made the two solutions and slowly poured them together with stirring. I next brought the resultant mess/(solution +precipitate) to a boil for 15-20min. I found the color was quite similar(a little lighter I guess) to what I have made with the hour long process with very vigorous magnetic stirring at ~80C. The crystals were of course tiny though.

You are right about the NaOH I think. I can actually see the little NaOH prills glistening right up with moisture, and that in 5-10seconds on the scale boat. I must admit, I have been adding an extra 0.1-0.2g to compensate. Yeah, I really ought to do something better in this respect.

I am making more NaNO3 right now, for a good TNP nitration. I have the capability of doing magnetic stirring through the whole nitration now. I have always felt my TNP was just a little too insensitive. Also, the Picric Acid solution seems a bit orangey, even before adding the NaOH. I don't know about the other lower nitro compounds, but Dinitrophenol makes reddish colored solutions doesn't it? Red plus yellow= orange?

Thanks for the advice, I will try and do something better with the NaOH. Maybe if I dried it well in the oven then weighed it quickly? Your idea would be much more accurate though.


[Edited on 1-8-2010 by Hennig Brand]
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[*] posted on 1-8-2010 at 13:57


You could use bicarbonate of soda for your neutralization finishing and watch for the end of effervescence of sprinkled crystals on contact as a visual endpoint. And you don't need the picric acid in solution, a suspension in hot water is fine there, as the heat and concentration with some bright light and close visual inspection will show you the endpoint pretty close when using bicarbonate to neutralize.
Sodium picrate is a lot more soluble than picric acid so the suspension will quickly convert to a solution as the picric acid is neutralized.

Maybe weigh out 90% of your neutralization equivalent of solid NaOH and just heap that in, and weigh out maybe the remaining projected amount needed to neutralize as bicarbonate, with maybe an additional 5%. Then just go with the finishing by small additions watching for the endpoint. Of course when it ceases to effervesce on contact, cease the additions of sprinkles of a few crystals at a time and call that close enough.

[Edited on 1-8-2010 by Rosco Bodine]
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[*] posted on 1-8-2010 at 23:14


Phenol can be nitrated with 70% nitric acid, if gently heated.
http://www.google.com/imgres?imgurl=http://www.chemistry-blo...

Phenol can also be nitrated with Cu(NO3)2 in acetic anhydride
"with copper(II) nitrate in acetic anhydride or nitric acid/acetic acid mixtures gives high yields of the corresponding mononitro compounds"
ci.nii.ac.jp/naid/110003651630

That more concentrated HNO3 is not required should not be surprising, given that even 50% HNO3 solution can slowly burn through plastic over the period of a year.
The more dilute HNO3 is, the less NO2+ ions are favored in equilibrium.

Another reaction that was seen was
3Fe(NO3)2 --> Fe2O3 + Fe(NO3)3 + 4NO2 + NO

Fe(II) nitrate can be made by dissolving iron with very dilute nitric acid, or using HCl on Fe to make FeCl2, then adding sodium bicarbonate to precipitate out Fe(CO3)2, then either heating the FeCO3 with ammonium nitrate, or simply adding very dilute nitric acid. Ammonium nitrate can be made from a mixture of sodium nitrate and ammonium sulfate, the sodium sulfate being less soluble when the solution is cold (4.7 g per 100 mL at 0degC), leaving NH4NO3 in solution.

The action of nitric oxide in the presence of oxygen can oxidize substances that oxygen alone cannot. One would wonder whether
a little nitric oxide in excess oxygen and sulfur dioxide would not create some sulfur trioxide (which would likely further react to form nitrosyl sulfate).It would be important to have the gases free of any trace of water.
NO + O2 --> ONOO
2ONOO --> 2NO2 + O2 These two reactions are just guesses as to what the radical chemistry actually is.
"This conversion has been speculated as occurring via the ONOONO intermediate."(wiki)
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[*] posted on 2-8-2010 at 04:51


Quote: Originally posted by Hennig Brand  
I shouldn't maybe be admitting to this, but I think it does illustrate something(maybe). The first couple of times I made(tried) Basic LP I literally..........


Please don't ever feel uptight about examining an action that later on you may feel was unproductive. No one learns anything by always doing things correctly. If we all did things in a manner that yielded what we were after.....where is the learning process?

Even when a synthesis is successful, there are things that can be gleaned from the experience; you can trust me on that! :P



[Edited on 2-8-2010 by quicksilver]




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[*] posted on 2-8-2010 at 09:51


@Rosco
That sound like a good way to handle the TNP neutralization. I think I'll try that next time.

@Quicksilver
I like to try different things, quite often by trying to take a short cut. Often times though I end up eventually doing more or less what the synthesis suggested. I usually find (eventually) that most processes in a synthesis were for good reasons, that I just wasn't aware of previously. I think you are right though, when doing things differently (or improperly even) one can learn a lot. Probably alot of things that wouldn't have been learned had everything gone smoothly.

I am going to see if I can do little better with my TNP and Picrate syntheses. I have a week or so work trip shortly, so it may be after that. I will post results, when I figure a couple things out. Thanks for the help.
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[*] posted on 2-8-2010 at 15:07


By the way, using a microscope is a very sharp idea when working with lead azide. Taking a totally random tiny sample & examining it for any needle crystals can save you from a serious tragedy. It's a standard in industry. Needle crystals as you know are totally unacceptable in lead azide & @ 100x you should be able to see 'em.



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[*] posted on 2-8-2010 at 15:15
"Different instructions" Try this...


Conversion of Morphine into Picric Acid. P. Chastaing. (Comptes
Rendus, xciv., 44.) The phenolic character of morphine recently
pointed out by the author, and also by E. Grimanx (YearBook of
Pharmacy, 1881, 22), receives farther confirmation from a very
interesting observation recorded in his present paper. By the action
of nitric acid on morphine, an acid product of the formula C10H9NO9
is obtained, which, when heated with water at 100° under pressure,
yields trinitrophenol or picric acid.

Year Book of Pharmacy 1894 [Google.com/books]

Other ref. suggest treating the product obtained w/ fuming NA.
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[*] posted on 3-8-2010 at 04:27


When adding the ASA to the H2SO4, I find if I stir vigorously the ASA will dissolve quickly a spoonful at a time. If I let the ASA crystals sit on the top of the H2SO4(even for a relatively short time), it clumps together and is very hard to make dissolve. Has the ASA become degraded in some way, by not dissolving it quickly? Just curious if some of my TNP contamination problems could be originating from the Sulfonation. I bet Rosco knows if a person could botch a Sulfonation. Quite often I have made a bit of this insoluble material and it takes forever to dissolve it.

BTW after Googling it seems that Picric Acid solutions in water are only yellow when fairly dilute, so orange is normal. I guess I knew that already, trying to find a problem that isn't there I guess.


[Edited on 3-8-2010 by Hennig Brand]
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[*] posted on 3-8-2010 at 16:12


Ive seen the exact same thing with dissolving the ASA in H2SO4 so to releive any muscle strain and improve mixing w/o any clumping at all I imp. a stir stick for a hand drill by heating and bending broken std glass stir rod.Made very short work of the ASA mixing portion of the synthesis and vigourous prolonged stirring was devoted to other time sensitive tasks. allowed Better organization besides the superior mixing as I dont have a magnetic stirrer or my IMP overhead stirrer completed.

Now that it seems most of the interested parties are present I have a question and observation concerning what if any major differences
are ther in performance between LA,MF,PB picrate,even PB styphnate a material I had thought most ofetn encountered in NC primers.If I were to just peruse the lists of VODs densitys etc. I would have to come to the conclusion they are all relatively closely matched.Even if I take into consideration the different methodologys in testing,circumstances etc.
All of the sources rate these 3 as roughly similar as far as I can tell.
I readilly admit i have not experienced PB azide,on paper,they all seem quite similar in density, vod and relative brisance in fact PB picrate is most often listed with ahigher RB than the other 2 ,LA often listed as having the least RB compared to TNT.I wont list all relavent
info Ive seen butI have LA listed at a density of 4.6 gr cm3 5300mps.
HG fulminate isnt far behind at maybe 5200 @ 4.2/IIRC RB was listed in the neighborhood of 37/47% LA,HG fulminate at the higher end and plain PB azide @ 4400 MPS .67 RB/2.8 gr cm3?And the painPB picrate/HG Fulminate can be improved upon with the addition of K chlorate and /or AL powder. I expect some discrepancy in measurements but...Subjectively PB picrate made with an excess of PA(2/1.2 pts PA/PB monoxide( with a dirty yellow orange coloration while still wet w/methanol is a darker orange when dry and has a gritty feel.What can i say about the fulminate,not purified simply washed still a grey
colored powder but fully capable of det comp caps w/PA.They seemed
subjectively, to have similar power,a small paper matchead size of loose picrate material in al foil heated to det on a stove produced a smart,sharp crack
on det.Very similar to HG fulminate.What am I missing?Respectfully Pndr.

Perhaps further testing using a test plate of sheet metal to either measure the dent depth /width or better, penetration when the cap placed on end and detonated leaving a hole punch effect.My main concern however is a plain PB picrate, maybe a composition with a chlorate/AL powder would detonate reliably a comp cap with PA as the base charge.

Finally Im likely going to have to visit an archery shop for some hopefully inexpensive scraps of carbon fiber shaft material to stiffen a forend in comb w/epoxy.I havent seen a carbon fiber arrow shaft would your opinions be AL arrow shaft material or possibly carbon fiber?I havent a clue as to inside diameters either or bursting strenghth.I dont think I want excessive burst strenghth.However the description of anodized hardened al shaft material sounds superior to soft mallebale AL tubing.

[Edited on 4-8-2010 by grndpndr]

[Edited on 4-8-2010 by grndpndr]

[Edited on 4-8-2010 by grndpndr]
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[*] posted on 3-8-2010 at 16:33


I would imagine that letting the ASA sit upon the acid would form a layer of oxidized material = problems. Sulfonation technique is critical to many nitro phenols.



***Addressing the "Arrow question": I would add that I am very familiar with carbon fiber arrows and they take a quality saw to cut. They will splinter like crazy if anything but a fine scroll saw blade at high speed is used to cut them.
IMO they are fantastic for target archery. But for alternative uses, quality Easton aluminum is the way to go. I wouldn't steer you wrong there. - They (CF arrows) even leave splinters in meat on occasion and many folks won't hunt with them what-so-ever.
-=Easton Aluminum XX75 at 2215 should come close to 6mm cap body=-



[Edited on 4-8-2010 by quicksilver]

[Edited on 4-8-2010 by quicksilver]




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[*] posted on 3-8-2010 at 17:06


I have them in mind to reinforce a somewhat flexible older generation GI fiberglass Item. Ill keep the splintering in mind perhaps best for the shop to do any cutting.The AL tubing sounds better
for ITS intended use..

Any thoughts as to the seeming similaritys in the heavy metals based primarys specs?:(

[Edited on 4-8-2010 by grndpndr]
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[*] posted on 3-8-2010 at 17:48


Quote: Originally posted by quicksilver  


Legard publishes one of the most questionable of any I have ever read wherein he uses one liter of 98% H2SO4 to 50gr of phloroglucinol. The actual nitration was 124ml 98% H2SO4 / 76ml HNO3 70% {yes: going back & forth between volume and weight measurements.}


----
Try US Patent 4 434 304 issued to the US Navy 1984 which uses
1 L of H2SO4 &c.
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[*] posted on 4-8-2010 at 05:16


Quote: Originally posted by The WiZard is In  

----
Try US Patent 4 434 304 issued to the US Navy 1984 which uses
1 L of H2SO4 &c.


(0616)
Jeez...I grabbed that right away & you were right on the money. I am seriously impressed. I really DID look quite a bit.
I had become numb trying to find his patents or applications.
-=Follow-up=- (0633)
I edited the previous post as I was wrong: it existed (as seemingly wasteful as it was; but that's another issue). I snagged the actual patent as I really wanted to understand why such a lop-sided level of materials were used & perhaps the notations would help more than any abstract.

QUOTE:
"Any thoughts as to the seeming similaritys in the heavy metals based primarys specs?:("

In what regard? In reference to BLP?




[Edited on 4-8-2010 by quicksilver]




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[*] posted on 4-8-2010 at 05:38


Quote: Originally posted by quicksilver  
Quote: Originally posted by The WiZard is In  

----
Try US Patent 4 434 304 issued to the US Navy 1984 which uses
1 L of H2SO4 &c.



Jeez...I seriously need to grab that. If you found it (which I think you did) I am seriously impressed. I really DID look quite a bit.
So: you found one that used one liter at 50grams? And it was phloroglucanol? That must be the one. I had become numb trying to find his patents or applications.



Didn't take seconds w/ Google.com/patents and it is
listed in Ararwal and Hogdson's The Organic Chemistry of Explosives

By da there is a patents on turning picric acid into trinitrophloroglucinol and triaminotrinitrobenzene (TATB)
US 7057073.
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[*] posted on 4-8-2010 at 05:52


I'm going to check into those as they sound fascinating. But one thing I've found with later dated patents is that (occasionally) they omit "trade secrets" that may be vital. It's apparently legal for them to do that & patent lawyers know how to phrase it so they can keep some stuff out. Most of the trade secret stuff was from about the 1970's forward.; at least this was what I had been told.

With the level of acid used in trinitrophloroglucinol (if indeed that is a standard practice & not a unique patent for a specific outcome), I can see no reason not to stay with TN Resorcinol for a lead salt that's highly heat sensitive. TATB on the other hand has a lot of utility. But regardless, I appreciate the tip!


EDIT:

A fantastic patent!. Much thanks.
One quote made me chuckle: "The starting material (phloroglucinol) is about $50/lb (bulk quantities). It is unlikely that the 4-step process will be competitive with processes utilizing significantly less expensive starting materials. "
So I was not the only one that thought a synthesis of TNPG was an expensive proposition, especially with large levels of acid on top of that cost.........




On another subject, I don't know where your specific interests lay but I certainly hope that you are building a substantial library of your own. I really don't think we will be able to access all this "specific" knowledge-base [with little or no restrictions] in the years to come.

[Edited on 4-8-2010 by quicksilver]




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[*] posted on 5-8-2010 at 06:56


I was wondering if Rosco or Quicksilver could explain the best way to tackle the Sulfonation of ASA. Thanks.
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[*] posted on 5-8-2010 at 11:04


If you will look on page 2 of the thread on crystal growth and preparative details you will see that if you first heat your stirred H2SO4 to 80C and sprinkle the ASA into the vortex slowly, feeding it more and more very gradually as the earlier addition dissolves, the process goes smoothly.

Here's a link http://www.sciencemadness.org/talk/viewthread.php?tid=4457&a...

The formatting is fouled up on the page 3 of the other thread because of the excessive pixel width of the pictures by pdb. Perhaps a moderator can edit the formatting so that page 3 will display normally on that other thread.

http://www.youtube.com/watch?v=V83JR2IoI8k&fmt=18 She Blinded Me With Science :( ;) :D :cool:

[Edited on 5-8-2010 by Rosco Bodine]
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[*] posted on 5-8-2010 at 14:14


Now that's what I'm talkin about. I've got to start looking around the forum a little more. No doubt there are more goodies.
What I was learning from originally was something you posted quite a while ago on the now defunct Rogue Sci. You run a pretty tight experiment. Thanks Rosco.

You answered a question I had about the foaming issue as well. I have been a little sloppy, and trying to add the nitrate as quickly as possible, keeping the temperature at a reasonable level though. While adding the last third of the nitrate I didn't slow down addition at all, and consequently I always get this big foam, and it won't go back down really (or at least not easily). I wonder how much unreacted material is in that foam? Slowing nitrate addition down for the last third would make a big difference.

[Edited on 5-8-2010 by Hennig Brand]
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[*] posted on 5-8-2010 at 17:13


I save as much as possible both in a paper format and electronically.
and as much other threataned resources as possible.

What i meant by similarity was the published similaritys in det vel /densitys and excepting plain PB picrates alleged relative brisance of .67 .Similar brisance but apparently less with HG ful,LA,LS of .32/47 RB?
From what Ive read these various primarys are close in all the important areas OT RB.Of course different testing methods etc affect results but when different sources are pretty consistent.I do question exactly why plain LP made with excess PA/ sbstantially less PB monoxide is allegedly as inferior to MF,LA,LS etc.I(ts not relayed in the raw performance data?

I ran across a sci paper 'abstract' called "synthesis and prop of Lead picrates" in a japanese journal the papers entirety would be fascinating I believe but aquitring it..the only interestin/useful tidbits was the heat of decomp of PB picrate was less that PA useful in designing a cap material based on PB picrate and also that PB picra had high strike sensitivity compared to friction sensitivity believed due to the crstaline H2O contained.Lastly LP did not have a prop of fusion.FWIW I thought a modern look at the material could be enlightening.
FWIW the Journal Title is 'SCI,technol ,energ. mater' Vol 65 ISSN 1347 9466

My laymans question is how do iI square the reported performance of these various primarys were discussing with the alleged inadequacies of basic LP, even FM in its proven ability to high order det a PA base charge of crystaline PA pressed to less than max density 1.4/1.6.Low temp of LP det can be addresse as can its OB increasing brisance/power beyond its ballpark of 4400mps .67 RB the RB exceeds that of LA,MF etc and det vel is off by 800 mps compared to LA @ max density.How do I sqaure that with alleged performances or lack theroff? LP did seem to be a popular material perhaps with the addition of K chlorate and/or AL powder but MF also benefitted from this approach.Assuming one were operating on the KISS principle, very appropriate in my case!Why would I not assume that these materials were basically very similar at least in the advertised performance parameters?Enlighten a layman
his only attribute thus far the sense hopefully to not overmatch his capabilitys.:D


Purely subjective observation I have noted what seemed to be a higher brisance or det vel with the LP made w/powerlabs simple synthesis, ratios where a large excess of PA ,2pts /1.2 PA/ LM is used resulting in again subjective comparison of container pieces of a similar test involving AL foil enclosed LA the size of a small paper matchhead.powerlabs synth resulting in what su
bjectively seemed a more vigorous detonation and flakes of the AL corfinement found compared to the other still very energetic detonation of the LP with equal parts of PA/Lead monoxide 'Megalomania' but far larger remnants of the foil container.Crude and subjective but I wonder if more precise testing were conducted if the initial observations wouldnt bear me out.Simple observation is crude and very subjetive skewed to what one wants to see but it is basic to science at least at one time?Thanks, respectfully and inquisitive,PNDR:D

[Edited on 6-8-2010 by grndpndr]

[Edited on 6-8-2010 by grndpndr]
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[*] posted on 5-8-2010 at 19:14
Lead picrate primers


No. 391, July. A new fulminate with lead picrate as Its base.
The American chemist, Volume 5, 1875.


—M. Prat.—The author has substituted a composition containing
lead picrate for the fulminate of mercury ordinarily used in the
percussion cap manufactory at Bordeaux. The picrate is produced
by precipitating a solution of ammonium picrate with lead
acetate, washing and pressing out. The still moist cake thus
obtained is mixed with potassium chlorate, finely pulverized, in
the proportions of equal equivalents, and made into a paste with
gum trauacanth. Experiments show that while an equivalent of
common power gives 8 volumes of gas, and one of mercury
fulminate gives 10 volumes, an equivalent of the picrate powder
gives 36 volumes. Even for equal weights, the volumes of gas are
respectively 33, 23, and 36 volumes.

[Monit scient [3] iv 665, Jahresb f Chem 1874, 1124]
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