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Author: Subject: Hydrazine
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[*] posted on 11-5-2005 at 12:43


The problem may have been that my NaOH was in the form of rather large granules (2-3mm) and also the very small amount, which I should have heated instead of cooled.

My HS is not impure homever, as the freebasing in ethanol is extremely exothermic, as I've described earlier.

Freebasing with ethanol is just a better method for small batches, and that's what I want.

Larger amounts might work better without ethanol, but I'm working on a small scale here.

BTW, about azides again: for 0,1 mol Hydrazine, I use 0,18- 0,2 mol IPN. Is that okay? (No nitrite is lost via transesterification, as I keep the reaction vessel tightly closed)

Today I used the hydrazine extract to make another batch of NaN3, this time with only 50ml of reaction mixture, and the reaction set in much more rapidly. I added one third of the IPN to the ice- cold hydrazine/NaOH solution and took it out of the ice bath. It became cloudy after about 15 minutes of warming up. I've put it into the ice bath again and added the whole rest of IPN at once (all with strong stirring). Then I tightly closed the flask and I'm leaving it in the ice bath over night. The ice bath slowly warms up and allows the reaction to proceed slowly.

[Edited on 11-5-2005 by garage chemist]
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[*] posted on 11-5-2005 at 14:25


Quote:
Originally posted by garage chemist
The problem may have been that my NaOH was in the form of rather large granules (2-3mm) and also the very small amount, which I should have heated instead of cooled.


Yes that is the reason for the sluggish reaction , the state of subdivision of the
reactant is limiting the contact area .
With that coarse material , it may hurt nothing at all to simply dump it all in together at once , even to kick it a little with a few drops only of water .

The granulation of the NaOH which I have been using is very fine , a little more coarse than sugar . The fine granulation
reacts on contact and completes in seconds . So your slow reaction is from the rock salt like chunks being slow to dissolve .

Quote:

My HS is not impure homever, as the freebasing in ethanol is extremely exothermic, as I've described earlier.

Freebasing with ethanol is just a better method for small batches, and that's what I want.


As a general conclusion that is premature . I still think that at least to the point of the dihydrazine sulfate intermediate the aqueous system would prove most efficient . A little heat may change the result you are getting . But
if the yields are good the way you are doing it then that is what counts .

Quote:

Larger amounts might work better without ethanol, but I'm working on a small scale here.


Yes , the scale and concentration and
what you are trying to do within a given volume influences your choice of method ,
and the thermal considerations are no small factor . I tend to work with what
some would consider huge batches , but
having an industrial background has distorted my perspective towards molar
instead of millimolar quantities , unless caution about some stabilty issue or toxicity finds me working with "mini" scale . I dislike working with very small quantities when doing reactions about which I have confidence , seeing the same amount of labor and steps required can be scaled up greatly and then the " stash " of the desired material
is increased , having made the effort more
worthwhile . To me a modest batch of NaN3 is 75 grams or more from a liter of
methanolic Hydrazine Extract :D

Quote:

BTW, about azides again: for 0,1 mol Hydrazine, I use 0,18- 0,2 mol IPN. Is that okay? (No nitrite is lost via transesterification, as I keep the reaction vessel tightly closed)


Actually you don't want too much excess of nitrite , as it will decompose the azide already produced and reduce the yields .
I wouldn't go beyond 15-25% above theoretical on the nitrite if using IPN ,
or ethylene glycol dinitrite , for nitrosation
of an ethanolic extract . And you don't want the reaction mixture too cold , nor would it be recommended to have a sealed container with no overpressure relief , because IIRC you can get nitrogen buildup from this reaction .

Quote:

Today I used the hydrazine extract to make another batch of NaN3, this time with only 50ml of reaction mixture, and the reaction set in much more rapidly. I added one third of the IPN to the ice- cold hydrazine/NaOH solution and took it out of the ice bath. It became cloudy after about 15 minutes of warming up. I've put it into the ice bath again and added the whole rest of IPN at once (all with strong stirring). Then I tightly closed the flask and I'm leaving it in the ice bath over night. The ice bath slowly warms up and allows the reaction to proceed slowly.

[Edited on 11-5-2005 by garage chemist]


What I have observed with the reaction run in methanol is that there definitely is an induction period for the reaction before
the sodium azide begins to precipitate ,
and it may be that the water present causes the initial product to be held in solution until saturated and then precipitation begins , and continues at about the same rate as nitrite is added .
The crystals will be a bit more coarse I think with gradual addition of the nitrite ,
to the stirred mixture . If you save the residual alcohol solution from filtration ,
you can bring it to boiling to drive off
some of the water adding some makeup
alcohol to the mixture as needed , and after cooling you can add maybe one fourth the volume of toluene , and a second crop of less pure azide will precipitate from the cloudy solution .
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[*] posted on 12-5-2005 at 13:31


ARRGH!!! I only washed the NaN3 with denatured ethanol (non- purified, since I thought that all the hydrazine had reacted) and the ketazine formed again! An oily blob is in the filtrate and the NaN3 leaves a black residue after deflagration!

This is a major drawback of the diazotation in ethanol.
The (purified!) ethanol also turned yellow
during the diazotation, indicating that it was not pure.

The strange thing is that the hydrazine extract with NaOH did not form any precipitate and stayed totally clear before the IPN was added (I left it to stand overnight)!
The Nitrite also played a role, I think.
Or the azide?
I'm sure that there is some other junk in my "ethanol" besides the standard MEK denaturant.

I really should switch brands or better buy some absolute ethanol denatured with petrol ether or toluene.

PS: Thanks a lot for your very informative posts, Rosco! Your help is much appreciated.

[Edited on 12-5-2005 by garage chemist]
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[*] posted on 12-5-2005 at 15:52


Quote:
Originally posted by garage chemist

The (purified!) ethanol also turned yellow
during the diazotation, indicating that it was not pure.
Quote:


The yellow color to the reaction mixture is normal when organic nitrite is present in the cold mixture . After you estimate the reaction in the cold is completed , you can heat the mixture and drive off the nitrite in solution , and the mixture will clarify .

Quote:

The strange thing is that the hydrazine extract with NaOH did not form any precipitate and stayed totally clear before the IPN was added (I left it to stand overnight)!


Probably there is little carryover of any carbonate or sulfate when the alcohol extraction is not done hot . Or else these
impurities are less soluble in ethanol .
Try storing the extract in the freezer overnight and see if any small precipitate
settles out . It is for me a very small amount , which settles onto the glass .

Quote:

The Nitrite also played a role, I think.
Or the azide?
I'm sure that there is some other junk in my "ethanol" besides the standard MEK denaturant.


The most common denaturant is methanol . No problem with any azine formation is there . Though you will lose some nitrite due to formation of methyl nitrite , it shouldn't be so much a problem since the concentration of methanol is low . In a cold mixture a lot of the methyl nitrite will actually react before it is lost .

Quote:

I really should switch brands or better buy some absolute ethanol denatured with petrol ether or toluene.


Check the label or the MSDS for the product and it should say what denaturant is used . Honestly I didn't think of the azine formation when I suggested a non-methanol denatured ethanol . Sorry for that oversight . The methanol denaturant would be preferable
to a ketone denaturant . My foulup there .
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[*] posted on 12-5-2005 at 19:17


Found the Gmelin's reference mentioned earlier in 23, 565 (1936):

Hydrazoniumborat (N2H5)2H4(B4O7)3. Beim Neutralisieren einer Lsg. von krystallisierter
Borsäure mit 50%iger N2H5OH-Lsg., Einengen auf dem Wasserbad und über H2S04 erhält man rhomb.
Krystalle des 10-Hydrats (N2H5)2H4(B4O7)3.10H2O. Verwittert leicht und geht im Vak. über H2SO4
in das 5-Hydrat (N2H5)2H4(B4O7)3.5 H2O über. Beim Erhitzen auf 100° entsteht das wasserfreie
Salz, bei 250° bis 260° (N2H4)2(B2O3)6; oberhalb 260° schmilzt die Subst. und zersetzt sich dabei in
B203 und N2H4, A. Dshawachow (J. Russ. Ges. [chem.] 34 [1902] 227; C. 1902 I 1393).

"C." stands for Chemisches Central-blatt, perhaps that abstract has more detail, short of someone finding the Russian article.
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[*] posted on 17-5-2005 at 11:57


Thanks, S.C. Wack. This seems to be the easiest way to make anhydrous hydrazine.

Today, I tried to make HS with 2,8% NaOCl.
The amounts of NaOH, urea, gelatin, HCl and H2SO4 were adjusted according to the NaOCl content.
On adding the urea/gelatin to the basified NaOCl at 10°C, nothing happened. No foam, no heating. I slowly heated the solution to 60°C and held it there for 30 minutes (the color was a bit yellowish), then I heated it to the boling point (it turned almost colorless).
I cooled it down and added the calculated amount of HCl and the calculated amount of H2SO4 (only very little gas was evolved). Nothing precipitated.
I checked the pH of the solution: VERY alkaline. Strange! I added more HCl until it was acidic. LOTS of gas and foam were now produced!
On cooling, still nothing precipitated. There is a very small amount (about 0,1g) fluffy "precipitate" which doesn't settle.

This was a failure.
My next experiment will be the production of 10% NaOCl from NaOH and chlorine and then production of HS from this.

EDIT: and if this doesn't work either, I'll try the chlorourea process.

[Edited on 17-5-2005 by garage chemist]
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[*] posted on 17-5-2005 at 18:45


If chlorination is going to be a step in your
hydrazine synthesis , you should try the chlorourea method first ,
since it simplifies the rest of the synthesis and should produce a higher yield than the alternative . The hypochlorite and urea method is already well known to work , so experimenting with the relatively little known chlorourea method would make a more interesting experiment . This has the chance of confirming a method
barely mentioned in the literature , while
chlorination of NaOH is routine .
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[*] posted on 18-5-2005 at 03:19


OK, all right.

Could there be some unknown hazards with the chlorourea process? The worst- case scenario would be the formation of nitrogen trichloride.:o
Interestingly, NaOCl + urea also yields large amounts of NCl3, but only under special conditions (NaOCl added to a mixture of urea and sulfuric acid- here, chlorine is first produced from the NaOCl and acid). There was a thread about this somewhere...

I'll try the chlorination of urea with very small amounts first and look if it's safe.
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[*] posted on 18-5-2005 at 07:41


Garage Chemist-I find that I have to heat the reaction with urea/hypochlorite from begining to end or the reaction will fail. This may have something to do with the low conc of the sodium hypochlorite used (it just says "less than 5%" on the bottle).
On another note, can anyone see a reason why acetone would be a bad choice to extract the hydrazine? I'm just thinking that it's easier to find pure than ethanol/methanol and probably won't give a phase separation like isopropyl will.
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[*] posted on 18-5-2005 at 07:44


Acetone certainly won't work, because it will react with the hydrazine. Actually, my problem were the trace amounts of ketones in my ethanol!
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[*] posted on 18-5-2005 at 12:10


Another factor that could be attacking your yields of HS is when using low concentrations of NaOCL there is too much water in the mixture. HS is to some extent soluble in water and will remain in solution when the reaction is complete. This is where it is also imperative to follow a procedure such as Mr A's to the T. I may have overlooked this being mentioned earlier, if so, oops! I have used Mr A's procedure and it worked every time.



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[*] posted on 18-5-2005 at 12:12


Another factor that could be attacking your yields of HS is when using low concentrations of NaOCL there is too much water in the mixture. HS is to some extent soluble in water and will remain in solution when the reaction is complete. This is where it is also imperative to follow a procedure such as Mr A's to the T. I may have overlooked this being mentioned earlier, if so, oops! I have used Mr A's procedure and it worked every time.



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[*] posted on 18-5-2005 at 14:58


@ Mongo Blongo: Do you use DanKlorix? It is 2,8% NaOCl, it is written on the bottle (under "Anwendungen", it's rather hidden).
I was not able to get any HS with 2,8% NaOCl.

Anyway, I'll never use hypochlorite again, because today I tried the chlorourea process and IT WORKED!!!

Here's what I did:

In a 3-neck 250ml rbf equipped with a gas inlet tube whose tip had been pulled out into a "pipette tip" (the other two necks were simply left open), I put 20,5g urea.
In a beaker, I dissolved 0,2g gelatin (this is still necessary!) in 45ml warm distilled water.
This solution was added to the urea and it was stirred until the urea had dissolved.
A gas generator was set up (100ml rbf and pressure- equalized dropping funnel with gas outlet at the side) and charged with 10g TCCA (made into a slurry with 10ml water) and 34ml 25% HCl.
The HCl was slowly added to the TCCA, the chlorine bubbled through the urea/gelatin. The urea solution and TCCA were swirled from time to time to ensure complete reaction. The chlorine bubbles reacted completely, no chlorine smell was noticed.
When all the HCl was added, the TCCA/HCl sludge was heated to nearly the boiling point to expel all the residual chlorine.

In a 500ml rbf, 16g NaOH were dissolved in 40ml distilled water. To the resulting hot solution the chlorourea solution was added immediately and all at once. It was swirled to ensure complete mixing.
The solution went dark orange and white foam was produced, the solution approximately doubled its volume.
It looked EXACTLY like a normal batch of HS with hypochlorite!
It was slowly heated, the foam slowly subsided and the color became lighter.
When it was almost boiling, it was nearly colorless. It was left to cool.

While stirring with a magnetic stirrer, 60ml 25% HCl (a bit more than needed to neutralise the used NaOH) were slowly dripped in, CO2 was being produced, and the hydrazine fumes+HCl gas formed a white fog in the rbf.
18ml of conc. H2SO4 were diluted with 20ml water and slowly dripped into the well stirred mix. After about two thirds were added, a precipitate suddenly occured.
The rest of the H2SO4 was added more slowly in order to produce larger crystals.

It was left to cool to room temperature, then it was cooled to 0°C in an ice bath. 100ml of the supernanant liquid were set aside to wash residual crystals out of the rbf.
It was filtered through a coffee filter and washed with a small amount of ice- cold distilled water and then with some ethanol.

It's drying at the moment. The theoretical yield (100%) would be 13g, but some HS stays in solution of course.
Tomorrow I'll weigh it. It looks like about 8 grams.

I can think of several improvements to this reaction:

The most important thing is to make sure that one uses exactly the right amount of chlorine. The production from TCCA+HCl is very cheap, but this reaction doesn't go to completion (that's why I used a bit more than the theoretical amount). Also, the commercially available material is only 92% TCCA. I will have to find out the amount of TCCA that produces exactly 0,1 mol of chlorine. I'll either have to collect the gas over water (via pneumatic bowl) or use it in a reaction where the product can be titrated.

Another important thing would be to use more concentrated solutions. Especially the NaOH can surely be used in a 50% solution (saturated). The urea can also be used as a more concentrated solution (the patent actually uses a slurry, but this would hinder the reaction since the mix is not homogenous, so I'll use a saturated solution instead).

When a high enough concentration of reactants can be reached, it might become economic to distill off the hydrazine as the hydrate instead of precipitating it.

Maybe I should, after optimization, publicate the entire process as "Mr. Anonymous 2"? :D

[Edited on 18-5-2005 by garage chemist]
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[*] posted on 18-5-2005 at 15:57


Outstanding that the chlorourea method is confirmed . It should be so much easier
to form the monochlorourea and not have to deal with the exotherm and possible overchlorination as with forming sodium hypochlorite . I haven't studied
the patent closely but it seems possible
to perhaps combine the methods , using
a lower concentration of bleach with some extra NaOH to provide an even more
concentrated reaction mixture . Whether
the reaction mechanism is basically the same and if this could work , I am not sure . This is simply a variation on the idea I have already mentioned about using the lower strength bleach in a different way , strengthening it by basifying it further and chlorinating it to a higher concentration . I have an idea that
sodium hypochlorite is actually formed in situ when the monochlorourea is added to the NaOH solution . Indeed urea forms
clathrates and the monochlorourea may be a clathrate , essentially nothing but chlorine soaked up in the urea which swells like a sponge entrapping it , and then releasing it upon dissolving in the aqueous NaOH .

The conditions of pH and temperature also provide opportunity for steering the final result to be semicarbazide or hydrazine . If hydrazine sulfate is the intended product from some of the more diluted reaction mixtures , it may be helpful to increase the amount of H2SO4
by ten or fifteen percent on a molar basis ,
as the solubility of the HS decreases rapidly in any excess of sulfuric acid .
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[*] posted on 18-5-2005 at 16:03


Well done Garage Chemist!
I'd be really interested what yield you got, having done the Raschig process I know what a pain it is, and what large volumes have to be used!
I suppose one of the great advantages is the fact that small volumes are used from the beginning, avoiding this concentration step that is necessary with the Raschig process.

In other words, the hydrazine is already quite concentrated. I wonder if even smaller volumes for dissolution could be used. (edit:seems you mentioned this in an edit)

Oh, and why do you first use HCl to neutralise the NaOH, then H2SO4? Isn't it possible you have losses due to the more soluble hydrazine chloride? So why not using *only*H2SO4?


PS I hope you did a quick testrun before doing such large volumes - weren't you afraid of NCl3? ;)

Why also do you want to use exactly the right amount of chlorine? It might help to put up the reaction equation btw

Great work anyway!


[Edited on 19-5-2005 by chemoleo]




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[*] posted on 18-5-2005 at 16:22


I used HCl for the first neutralisation because when only using H2SO4, one gets huge amounts of glauber's salt (Na2SO4*10H2O) along with the HS if one cools too deep. The solubility of NaCl doesn't change with temperature, which permits stronger cooling to get more HS.

If I use too much chlorine, dichlorourea would begin to form, or worse, NCl3 (I am certain that it forms from urea and chlorine, but only in acidic environment- the excess urea helps keeping the pH basic).

I added the first bit of chlorine very slowly and checked very carefully for any yellow color or oily droplets ( I know how it looks when NCl3 forms, having made it on purpose a long time ago- I also know the smell of it, which is VERY strong).

[Edited on 19-5-2005 by garage chemist]
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[*] posted on 18-5-2005 at 17:00


Just a couple of thoughts that may be useful , if the reaction mechanism is what I suspect it may be , and the monochlorourea / dichlorourea are unstable not well defined compounds chemically , but inclusion compounds , which are " sponges " for adsorbed chlorine . The Schestakow type reaction
is not adversely affected by excess NaOH ,
and the quantities I arrived at were for sufficiency and economy for the reaction using the sodium hypochlorite already formed in the usual way . But for the monochlorourea or polychlorinated urea
which may occur , it may be better to use a bit more total NaOH so that any excess chlorine is converted to hypochlorite . It is important to keep the ratio of urea to hypochlorite correct so there is no substantial excess of hypochlorite , and this should translate for the ratio of total chlorine to urea also . But it hurts nothing to have excess NaOH , it just requires more HCl for the intial neutralization . These ratios may vary some from what is best for the direct hypochlorite method may not be directly applicable to the monochlorourea method , but I suspect the ratios will be close enough that interchangeability is a valid starting point . Anyway , please do
try using the weaker bleach with NaOH ,
and then you need not worry about overchlorinating the urea , because you can have the unreacted urea present in an amount which will react with the hypochlorite already present in the bleach . This will avoid any danger for overchlorinating the urea , and at the same time will give a more concentrated reaction mixture .

When the foam is subsiding and you see
that happy bright orange color ......

Whew , I think it's gonna be alright
Yeah, the worst is over now .....

My reaction flask is shinin'
like a red rubber ball :D;):D;):D

All genius is seasoned with a sprinkle of madness ......

and for some of us , there is more of a sprinkle than for others :D

[Edited on 19-5-2005 by Rosco Bodine]

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[*] posted on 18-5-2005 at 18:53
Chlorine Simple Method


Thanks to Organikum for this file mentioned in another thread .

Chlorine is evolved from the reaction between TCCA and ordinary salt ,
forming sodium cyanurate as the byproduct .

How best this reaction might be used in hydrazine synthesis may be a basis for some interesting experiments .
It may be that a slurry of salt , urea , and TCCA would form the monochlorourea .
And then the mixture added to basified bleach could perhaps form hydrazine
which may precipitate immediately as the
slightly soluble hydrazine cyanurate .
This could be then filtered out or perhaps converted in situ to hydrazine sulfate
by adding sulfuric acid to the heated
and stirred mixture . Actually the cyanurate can be freebased so it may be
pointless to convert to the sulfate , if
the cyanurate is more desirable for freebasing . This would depend upon the solubility of sodium cyanurate in alcohol . The possibilities associated with the usefulness of the cyanurate in azide synthesis would need to be considered ,
including its potential to be used directly .

After I attach this patent for the Chlorine from TCCA and salt , I will make a subsequent post with the file attached regarding the hydrazine cyanurate . Hopefully it is clear what I am describing as the reason these reactions are related , and how the reactions may possibly be combined in a synthesis of hydrazine .

[Edited on 19-5-2005 by Rosco Bodine]

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[*] posted on 18-5-2005 at 19:21
Hydrazine Cyanurate


GB1073292 Hydrazinium Cyanurate

This is another means of precipitating a slightly soluble hydrazine salt which may be freebased by NaOH .

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[*] posted on 19-5-2005 at 03:11


The generation of Cl2 from TCCA and salt is very interesting, I haven't heard of such a reaction before. This will be one of my next experiments.
The precipitation of hydrazinium cyanurate from the mixture seemed like the ideal method to me first, but in the paper, it was also mentioned that monosodium cyanurate is insuluble in water. I'd be concerned about the purity of the precipitated HC, especially when an excess of NaOH was used.

From my used amounts of reactants, you can see that I used a bit over 0,3 mol urea, only 0,1 mol chlorine and 0,4 mol of NaOH. This provides an excess of urea and a further excess of NaOH and therefore absolutely no risk of urea overchlorination.

I don't think that the urea simply "adsorbs" the chlorine, because there was a strong chloramine (not chlorine!)- type smell over the chlorourea mixture.
The chlorine reacts with water to form HCl and HClO (an equilibrium, but it is strongly shifted to the right due to the basic environment). The HCl is immediately taken up by the urea to form urea hydrochloride, the same as with the generation of urea nitrate, just with HCl (and it stays in solution).
I'm sure that the HClO immediately reacts with urea to form N-chlorourea, because HClO is a very unstable compound (think of the rapid decomposion of acidified bleach!) and also very reactive.
You know the mechanism of the Hofmann degradation?

And you can be SURE that I'll never use any NaOCl products again. Not even as a supplementary chlorine donor in the chlorourea process. 100ml of my bleach only contain 2,8g NaOCl. You can't say that this would make any noticeable difference. It would just dilute the solution.

My next step will be the analysis of the chlorine- producing reaction and the determination of the required reactant amounts to make exactly 0,1 mol chlorine.
The TCCA/salt method will be used for this.

EDIT: The TCCA/salt method requires a vacuum. Therefore it isn't that useful.
HCl/TCCA will still be required.

[Edited on 19-5-2005 by garage chemist]
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[*] posted on 19-5-2005 at 05:17


My HS weighs 6,6g.
That's an approx. 50% yield from chlorine.
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[*] posted on 19-5-2005 at 07:39


I see what you mean about the 2.8% bleach not offering any advantage because of the dilution . But the idea
of combining the reactions could be useful
if you have easy access to stronger bleach .

The fumes which come off the chlorourea reaction should be avoided , it being unknown what exactly may be the toxicity
or precise nature of the odor .

The reactions which may form hydrazine are a balancing act against undesired side reactions which may also occur if the proportions of reactants are not optimal for the hydrazine reaction to prevail .

Excess urea will react with the hydrazine formed , resulting in a carbonamide and other byproducts . Even some of the CO2
reacts with and decreases the yield of hydrazine . Excess NaOH tends to mitigate the formation of such byproducts .

Ordinary household bleach is about 5% NaOCL . And about the same amount of salt is present also IIRC . What I am trying to say is that instead of using plain distilled water to make your concentrated NaOH solution for the decomposition of the chlorourea , to use the bleach and
an extra molar equivalent of NaOH with regards to the NaOCl present , and then
the added amount of NaOH you would use for decomposition of the chlorourea .
Simultaneously , use an extra amount of urea equivalent to the molar amount of NaOCl , and let that excess portion of the total urea remain as unchlorinated excess urea present in the slurry of urea being chlorinated to monochlorourea . When the chlorourea and unreacted urea mixture is added to the basified hypochlorite , the reaction should proceed to produce hydrazine from two precursors simultaneously , converting the monochlorourea as in your reported experiment , and also converting the unchlorinated urea by reaction with the hypochlorite . The reaction would be a marrying of the Shestakow reaction with its related monochlorourea reaction , which may actually be the same reaction
only having different means of bringing chlorine into the reaction . You see I suspect that sodium hypochlorite is an intermediate in the reaction by either route , whether it is formed in advance ,
by using bleach and urea for the reaction ,
or whether it forms in situ when chlorourea reacts with NaOH . The chlorourea reaction for hydrazine should be more exothermic and more rapid because the heat of reaction forming the hypochlorite is added to the usual exotherm for the hydrazine reaction which occurs subsequently . This theory may be all hogwash , and I have not studied this nor done any experiments to
test the theory . It just occurred to me that it is worth examining as a possibility .

With regards to the TCCA and salt reaction needing vacuum , not necessarily so if there is something present or added gradually which will react with the free chlorine and shift the equlibrium to the right . Anything which reacts with the chlorine produced could emulate the effect of vacuum and cause the TCCA and salt reaction to proceed . Again I have not tested this theory to see if monochlorourea would form , but it is a worthwhile possibility for experimentation .

All of these ideas are speculations for methods of concentrating the reaction mixture producing hydrazine and simplifying the preparation of the precursors , and some or none of these ideas may prove to have any validity or be workable . These ideas just seem to present some new angles to explore in regards to experiments with hydrazine , where TCCA is the new reactant whose potential usefulness is yet to be determined . The truth is that it would take a series of experiments to actually determine what are the advantages if any for applying any of these untested ideas .

[Edited on 19-5-2005 by Rosco Bodine]
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[*] posted on 19-5-2005 at 08:04


Do you think that 0,7g NaOCl (from the 20ml bleach used to dissolve the NaOH) with 20g urea have any measurable effect?

Using a stronger NaOH solution would raise the concentration of hydrazine in the resulting liquid much more than using bleach.
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[*] posted on 19-5-2005 at 08:16


Your message and my edit just passed each other in flight through cyberspace .

I understand exactly what you are saying and you are correct that with that low a concentration of bleach , there is likely no gain and probably a loss for trying to combine the methods .

Europeans need to riot in the streets demanding that their bleach be watered down no longer , that you are just not going to take it any more , paying top Euro for chlorox that has been " stepped on " by the middle man :D

But for those of us who can get 10% bleach at the grocery store , the possibility
of in effect doubling the concentration of the reaction mixture for the usual process
does have a certain appeal .
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[*] posted on 7-6-2005 at 17:47


I decided to try the chlorourea route to hydrazine sulfate today.
Generally I followed Garage Chemist’s method but made a few slight changes in temperature, timing and chlorine source.

In a 250ml beaker was added:
0.2 gm gelatin (Knox)
20.5 gm urea (Fisher a.c.s.)
45 ml water, R.O.
The beaker was warmed over a flame until contents dissolved then placed in an ice bath to chill.

A chlorine generator was cobbled together using a flask and addition funnel pretty much the same as Mr. Chemist’s set up. There in was placed:
12 gm of CaOCl (HTH containing 78% CaOCl & 22% unknown adulterant)
10 ml water, R.O.
30 ml HCl (hardware store brand 31%)

The chilled ( ~4c) urea/gelatin soln was placed in a 100 ml graduated cylinder and the chlorine was bubbled in through a glass pipette connected to generator using rubber tubing. The HCl was added slowly drop wise to CaOCl over a period of 15 min. The addition of the chlorine caused the temperature of the solution rise to about 30c. After the chlorine stopped coming over, the pipette was pulled out and the cylinder and contents allowed to rest. It was a lovely pale yellow color.

In a 1000 ml Erlenmeyer flask the following was added:
40 ml water R.O.
16 gm NaOH (Fisher NF/FCC)
2 in. octagon stir bar.
The flask was placed on a stirring hot plate and stirring begun. After the sodium hydroxide had dissolved, the temperature had only risen to ~55c due to the heat loss to the large flask.

The chlorourea was swiftly poured, in one portion, to the flask with the NaOH while stirring fast. The contents immediately foamed up to occupy at least 70% of the volume of the flask but there was no appreciable color change except for the lightening of color due to the foam. Stirring continued for 5 minutes further where upon the foam began to subside and the color turned slightly amber. Stirring was discontinued while the hotplate was turned up high and the flask covered with plastic wrap to keep out excess air. At this point the solution was no longer foaming at all and the temperature was probably 75c or so.

The flask was taken off the hot plate and left to rest, covered for 5 minutes then placed in a bowl of cool water. Ice was added then to further speed the cooling. After the contents cooled to about 5c it was put back on the stir plate and adjusted to a medium speed.
33 ml HCl (31.45%) was added in a slow stream with considerable frothing and white fumes, over the period of 1 to 2 minutes. Next, 21 ml H2SO4 (Fisher 95%) was added in a very slow stream in a few portions while trying to keep spattering to a minimum. The crystals began to form but not as rapidly as I would have expected but after a minute the crop was clearly good.

Once again the flask was removed from stirring and quickly cooled in an ice bath to 3 or 4c. The contents vacuum filtered and the supernant liquid used to wash the remaining crystals from the flask. A few ml of cold H2O was used as a wash then the vacuum was continued to remove as much excess moisture as could be gotten out.

The product was weighed at 12.83 grams while still slightly moist. I will weigh again after it is dry but expect the amount to be over 11 grams.

The whole process was straight forward, easy and I must say, fun to do. It took less than 1.5 hours to complete including set up and some clean up afterward. I plan on running a sample on the FTIR and comparing it to a sample of HS I made with reagent grade hydrazine hydrate and reagent grade H2SO4. I will post the results afterward.
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