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Polverone
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alternative oxidizers for hydrazine production
The production of hydrazine by oxidation of ammonia or urea with hypochlorites is well-known. Problems for the home experimenter:
Commonly available solutions of sodium hypochlorite and ammonia are very dilute, meaning that a lot of energy needs to go into concentrating the
reaction mixture before isolation of the hydrazine via precipitation of its sulfate, and this concentration stage can be fairly expected to further
reduce already-poor yields.
Urea can be used instead of ammonia, though the exact procedure escapes my mind since I am away from my home computer and references right now. This
means that the concentration of substance to be oxidized can be much higher.
However, the sodium hypochlorite solution is still dilute, and quite often full of materials that the experimenter doesn't want or need (sodium
hydroxide, sodium chloride, possibly chlorites or chlorates from photochemical degradation if the solution is old...)
Calcium hypochlorite is one possible alternative to sodium hypochlorite solution. It is far more concentrated than liquid bleaches, and more
economical for a given amount of oxidizing action. However, it is still impure to begin with, subject to degradation in storage, and it reacts with
sulfuric acid to form low-solubity CaSO4, which would contaminate precipitated hydrazine sulfate.
Lithium hypochlorite is supposedly available as a specialty pool/spa chemical in solid form in purities near 100%. But I've never seen it sold in
pool/spa centers, only online, and it's more expensive than other hypochlorites. It will also be very hygroscopic if it's like other lithium salts.
Since trichloroisocyanuric acid (TCCA, also known by a variety of other names) is a relatively mild, safe, and readily obtained oxidizer (again, from
swimming pool chemicals), I've been wondering lately if it could be used in place of the troublesome hypochlorites for hydrazine preparation. Since I
haven't looked at the chemistry involved in a while, I don't know if this has a chance of working. I thought I'd toss it out and see if it generated
any discussion before I return to my references & lab materials.
I found a page that said oxidation of ammonia in the presence of ketones, to form ketazines, and subsequent hydrolysis of ketazines to form hydrazine
was one current industrial method. Another, more recent method uses environmentally friendly H2O2 with ammonia in the presence of ketones (H2O2 +
ketones sounds like trouble to me...) That might be enough information to start a search if there's anyone out there with some spare time and an urge
to hunt through patent databases.
Any other novel ideas for hydrazine production? It's really the bottleneck in home production of azides. Whipping up ethyl nitrite is trivial, but
hydrazine's a bit more trouble. I could just order hydrazine sulfate, but where's the challenge in that, I ask you?
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Nick F
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What about persulphates? They're easily available in kg quantities as pool cleaners or something...
I'm not too sure about trichloroisocyanuric acid, I can't see a route by which it would work. Obviously that doesn't mean that it won't work, I'm just
saying that I personally can't see how it would.
Why not use Ca(OCl)2, ppte CaSO4 along with the hydrazine sulphate, filter it and then add it to boiling water, and filter out (very nearly all of)
the CaSO4, leaving a fairly pure hydrazine sulphate solution.
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kingspaz
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this may kind of be off topic but sometimes when i have a piss in a freshly bleached toilet there seems to be a reaction because a very strong choking
smell comes off. it doesn't smell of piss so its not that. i was wondering if it could be hydrazine from the reaction of the NaClO solution with urea
in the piss?
the unexamined life is not worth living to a human
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vulture
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Wouldn't that simply be ammonia? I would think NaClO would be banned for use in toilets if it actually produces hydrazine.
One shouldn't accept or resort to the mutilation of science to appease the mentally impaired.
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Microtek
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Actually yields of the NaOCl + NH3 reaction increases with the ratio of NH3 to NaOCl but decreases with concentration of both NH3 and NaOCl. The
information is from chemical abstracts and is reasonably old, but it is also my personal experience that pure 15 % hypochlorite gives less hydrazine
than three times as much 5 % soln...
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Polverone
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thanks
I didn't realize that. As I said, I'm away from my usual references right now so I'm working mostly from speculation and my flaky memory. Did you
separate hydrazine as the sulfate, distill the hydrate, or do none of the above? Concentrating the solution by boiling and then precipitating the
sulfate seems most straightforward, but energy-intensive. Also, what concentration of aqueous ammonia did you use with your hypochlorite? I realize
that some of these questions have been thoroughly covered before at the E&W Forum, so I should go do a search and read the archives there, but I
recall remarkably few people having claimed success at making their own hydrazine and then azides.
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Microtek
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As you may have seen, I have been conducting quite a lot of experiments with synthesis of good primary explosives. In my opinion DDNP would be ideal,
but since I have tried so many different methods and spent hundreds of hours in the lab and in the library and still can't get it to work, I've
decided to let it rest for the moment ( as I've done before ) and elaborate my azide procedure.
So here is what I've arrived at:
3 g gelatine is dissolved in 30-50 mL water and added with stirring to 200 mL 20% ammonia in a 1 liter beaker. This soln is placed on a hotplate (
portable electric stove ) heating at max power. 150 mL NaOCl 5% is added in one go, along with about 0.5 g Ca(OH)2 and the beaker is swirled a little
to proper mixing.
The soln is reduced to below 200 mL by boiling, and is cooled rapidly to 20 C.
It is then filtered through a single filterpaper over cloth to get the insoluble Ca-salts out. A few ice cubes are added to the soln to get it very
cold, and dilute H2SO4 ( I recommend 50 % by volume ) is added to precipitate the HS. About 20 mL dilute acid is needed ( if 50 % of course ).
Soln is left in a cold place such as the freezer for 30-60 minutes to complete precipitation. It is then filtered and washed with alcohol in the
filter.
Yield is about 6-7 grams hydrazine sulfate.
Now, for the azide fabrication I prefer isolating the hydrate by distillation which is not a problem if you don't mind a dilute solution. On the other
hand, I have made sodium azide before using hydrazine nitrate which I converted to the hydrate in situ by the addition of NaOH so I guess it depends
on what you need it for.
Anyways here goes:
6 grams of dry HS is placed in a retort ( or whatever ) and is wetted with a little water. Then a soln of 4 grams of NaOH in 30 mL water is added and
the retort is closed. More or less water can be used but if too little is used you might have corrosion problems or conceivably explosions though I
don't think it's as much of a problem as with anhydrous hydrazine. The retort is heated on a sand bath with cotton wool insulation to get a fast run,
and the contents are heated strongly to dryness.
For the azide production, the hydrazine hydrate is placed in a tall flask or in a reflux setup along with 2 grams NaOH.
And about 50 mL alcohol. The mix is heated to about 30 C and removed from the heater. An excess of isopropyl nitrite is added portion wise with a few
minutes between additions.
The flask is agitated occasionally. Once all the nitrite has been added, the mix is left for a few hours or overnight, and is then ready for use ( or
you can evaporate the liquid ).
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Polverone
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Thanks a lot for the comprehensive instructions. I may try that when I get some free time. DDNP interests me too; I've followed various discussions on
its preparation. What part seems to be the most problematic - reduction of picric acid to picramic, diazotization, preparation of precursors? Or is
the whole thing just trouble from beginning to end? I hesitate to tread where hundreds of hours of effort have lead to repeated failures, but I do
like a nice meaty challenge...
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Microtek
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Well my problem is that I have to prepare all the precursors and I'm not sure how sensitive the synthesis is to impure reagents. I use recrystallized
picric acid from aspirin which I'm pretty certain is good. The nitrite has been produced by various routes such as nitrate reduction with lead or
carbon but I've settled on bubbling NO+NO2 from reaction of HNO3 with starch through NaOH soln.
The reduction of the picric acid has been done with Na2S + Na2S2O3 directly from the reaction of NaOH with S, but I've also tried NaHS of a somewhat
higher purity by isolating ZnS from the above mixed solution, liberating H2S by addition of H2SO4 and bubbling the gas through NaOH soln.
The reduction has been done at both high and low temp and for differing lengths of time ( Though I've recently been convinced that it should be done
at about 80 C for 45-60 minutes ). I have tried isolating the picramic acid by addition of HCl and I have also tried diazotizing the Na-picramate
directly.
And this is just the tip of the iceberg. In a synthesis with so many steps, and with so many variations to make at each step
It can become overwhelming, especially because I can't get rid of that nagging doubt that it's the nitrite that isn't good enough. I can't imagine
why, but if I try to make isopropyl nitrite with it I don't get anything. Speaking of IP-nitrite, a really good method is setting up a gas generator
with 50 % HNO3 and starch, heating the flask and leading the gas into another flask with isopropyl alcohol and a two hole stopper. The HNO3/ starch
flas is heated to about 70 C at which point the redox reaction is self sustaining and heat need no longer be applied. The heat of rection between the
N2O3 equivalent gas and IPA is enough to evaporate the nitrite as it is formed and the gaseous product is lead into a final flask with crushed ice.
The method doesn't require much attention and is useful for producing large amounts as the yield is very good.
By the way, I have also thought about making DDNP by bubbling N2O3 through an alcoholic solution of picramic acid. This is what Griess did when he
discovered diazotisation so it should work. I haven't got around to it though.
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Nick F
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Well, it looks like you've done a lot more on this than I did (well done! I gave up!), but I eventually came to the conclusion that bubbling NO2/NO
through an alcoholic solution of picramic acid would be the best way. It'd solve most of the problems I had, such as the low solubility of picramic
acid in water. And there can be few side reactions if you purify the picramic acid well first, and it'd mean that impure KNO2 can be used, or the
method with starch like you posted. So it should work well. Maybe something like acetone or ethanoic acid would be a better solvent (if picramic acid
dissolves in it well enough) since it's less likely to be oxidised by the NO2/NO.
I'm just glad I don't have to look for a primary any more - I got 1kg of NaN3 
But I truly admire your determination, if I do something and it fails ten times then I give up. Only occaisionally did I get any DDNP, and even then I
got small yields.
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Polverone
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you raise my hopes
I have a kg of pure sodium sulfide that I can use, I think, to prepare pure sodium polysulfides. I also have a kg of pure NaNO2, so I don't have to
mess about with making it from scratch. It's easier to prepare ethyl nitrite than isopropyl (since the reaction happens faster), and for azide
production that's what I would use. If precursor impurities were your main obstacles, then maybe I'll succeed where you encountered many setbacks. But
just as likely not...
Nick F, you lucky guy! If you don't use that NaN3 for anything but making primaries then I think you have a lifetime's supply of detonators ahead of
you... Be my hero and try cyanuric azide (see Chemistry of Powder and Explosives).
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Nick F
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Lol, yeah my familly will have enough primary for generations!! And by the time it runs out, maybe someone will have sorted the DDNP synthesis out!
I would very much like to try cyanuric triazide and trinitrocyanuric acid, but don't know how to make the chloride easily once I've found cyanuric
acid, and I don't know if isocyanuric acid can be converted to cyanuric acid etc etc.
I'll have to do a bit of research and find out...
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Polverone
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I believe cyanuric chloride can be made by the reaction of HCN and Cl2 in the gas phase. Sounds fun and safe, yes? :-) Or you can treat cyanuric acid
with PCl5.
Actually, I figured that someone who can get a kg of NaN3 shouldn't have trouble buying cyanuric chloride.
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Nick F
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"the reaction of HCN and Cl2 in the gas phase."
Lol, yeah. I've always wanted to try a reaction involving nothing but war gases, here's my chance! 
Nah, I don't fancy that one much!
I was wondering about cyanuric acid with molten sulphur and chlorine gas though, what do you think? I can't buy PCl5 either :rolleyes:.
I might be able to get cyanuric trichloride, but not from a chem supplier in my country, I know that for a fact. I'll have to ask my sources...
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osamafon
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1mol. urea+1mol.NaClO=N2H4
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fluffy bunny
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DDNP
Microtek, i don't think its the purity of your chemicals that is failing your DDNP synthesis, well, not the nitrite anyway. I have also tried the
process many times using pure sodium nitrite, and everything else is pretty pure also except perhaps, the picric acid which was made from ASA, but
surely pure enough, i had recrystallised and washed it thoroughly.
I think one of the problems we may be having is that we may be reducing more than just one nitro group, and possibly getting diamino-nitrophenol
instead of amino-dinitrophenol, or it could be reducing the wrong nitro group? Anyway im sure the problem is with the picramic acid, as we all seem to
have inconsistant descriptions of our picramic acid. Mine is a dirty brown colour.
I've also attempted dissolving my picrmic acid in ethanol to do the method you were describing before, but its as insoluble in ethanol as water!
I haven't done much experimentation with DDNP lately, since i wasted all my TNP on nothing, but im sure the problem is with the reduction of TNP to
picramic acid.
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Madog
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about microteks method for hydrazine, and the conversion to azide.
can someone explain the reaction with the isoproppyl nitrite? and why its used, and if you could provide how well it works for you that would be
awsome.
thanks
Most people outgrow their pyro tendencies, we are the ones who\'s tendencies outgrew us.
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Theoretic
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May I suggest a completely different approach. High-temperature, anhydrous and molten. Specifically, reacting hypochlorite with molten urea.
Hypochlorite should be anhydrous, but chloride and impurities don't matter. Hydrazine's time of residence in the reaction mix is minimal
since it doesn't dissolve in molten ionic salts, so the side-reaction of hydrazine oxidation by hypochlorite is unnoticeable. This is the
equation for the reaction involving calcium hypochlorite:
2CO(NH2)2 + Ca(ClO)2 => 2CaCl2 + 2CO2 + 2N2H4.
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chloric1
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A good effort but..
Theoretic, Your thought process is quite novel BUT and (I do mean a big BUT), the high temperatures would decompose the hypochlorite immediately not
to mention ANY hydrazine formed would be oxidized or decomposed. You may try in an Argon or Nitrogen atmosphere but why bother. I have discovered a
far better method in the patent literature and in Chemical Technology Volume 13:580. You simple react hydrogen peroxide, methyl ethyl Ketone, and
ammonia in a 1:2:4 ratio at 50 Celcius at atmospheric pressure. This forms an azine that can hydrolise in acid at 90 to 100 celcius to the hydrazine
salt or if you are brave just heat the azine with water under 10 atm of pressure to 190 to 200 Celcius. I would just make hydrazine sulfate then add
NaOH with minimal water then take up resulting hyrazine hydrate in methanol. But thats just me.
Oh yes the azine process needs acetamide and disodium phosphate for the catalyst. Don't have yet as I wanted to try this over Thanksgiving
break . I do have acetic acid and urea which when heated together make acetamide.
[Edited on 11/18/2003 by chloric1]
[Edited on 11/18/2003 by chloric1]
Fellow molecular manipulator
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madscientist
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The reaction Theoretic posted works when performed in aqueous solution - I've tried it.
I weep at the sight of flaming acetic anhydride.
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Theoretic
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The MSDS for calcium hypochlorite says: "product decomposes at 180 C releasing oxygen gas". Well, maybe not only oxygen gas  , but that means it
can withstand the temperatures of molten urea (besides it reacts pretty quick - I assume -, it doesn't need to be heat-resistant). The MSDS sheet
for urea states its melting point as 133 C - nice - but in the same line of text urea's boiling point is stated as 135 C. And it's not just
one MSDS, it's two.
The same MSDS states that urea "Reacts with Sodium or Calcium Hypochlorite to form explosive Nitrogen Trichloride".
I assume that happens with a large excess of hypochlorite (would be a nice way of preparing NCl3), but not otherwise.
Besides, I think your concerns relate to the powder-it-fine-mix-thoroughly-it-heat-it method. There's no need for that, hypochlorite can be added
slowly, little by little. That way oxidation of hydrazine is avoided. The thermal decomposition of hydrazine - I don't think! Hydrazine's
boiling point is 112 C, and I assume it's stable at that temperature, and 135 C isn't far removed from that.
Another way of doing this (if you don't fancy the molten way for reasons unknown - ) is to dissolve the hypochlorite in an inert solvent so it forms a
layer with urea dissolved in another inert solvent. Hydrazine has to be soluble in the urea layer though. Oh, and one more thing - urea and the
hypochlorite have to be insoluble in each other's solvents.
Sounds too tedious - so here's a simpler one. Dissolve urea in a solvent that doesn't dissolve hydrazine but (preferably) dissolve the
hypochlorite. Place a layer of oil on top to stop anything escaping. I don't know if hydrazine is going to form a layer below the lot or between
urea and the oil, so in the latter case you'll have to harvest hydrazine after each addition of hypochlorite for obvious reasons.
Quote:
"The reaction Theoretic posted works when performed in aqueous solution - I've tried it."
Have you tried to add hypochlorite little by little so hydrazine already in solution would come into contact with hypochlorite as little as possible
(much less as compared to hypochlorite spread over the entire batch) and so that on every addition there's a local excess of urea at the reaction
site (and no hypochlorite at all elsewhere - )?
Have fun!
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Iv4
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Not much but it all I could find.Couldnt the hydrazine be distilied of or something?
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Theoretic
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Hydrazine could be distilled from concentrated solutions of NaOH or CaCl2 or any other dehydrating agent.
"I would just make hydrazine sulfate then add NaOH with minimal water then take up resulting hyrazine hydrate in methanol. But thats just
me."
Of course it's just you. I would consider using Ca(OH)2 or CaO instead
of NaOH.
(N2H5)2SO4 + Ca(OH)2 => CaSO4*2H2O + 2N2H4.
(N2H5)2SO4 + CaO => CaSO4*H2O + 2N2H4
The hydrazine is pure, anhydrous and ready to use. If you are dissatisfied with the CaSO4 slug getting in the way, just distill .
"ANY hydrazine formed would be oxidized or decomposed." Only the first 40 ml of hydrazine vapour or so would be. Then the oxygen would be
used up and H2O, N2 and (mostly) CO2 would provide a reliable gas blanket.
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chemoleo
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Hydrazine sulphate
Hmm, I don't see that much of a problem of making it.
1. you can easily get a NaOCl solution (fresh) by bubbling Cl2 into a NaOH solution, the former being obtained by dripping HCL into MnO2 or whatever.
2. You can easily generate a concentrated NH3 solution by mixing the corresponding amounts of (NH4)2SO4 (or whatever other salt you have) with NaOH.
Of course you will get Na2SO4 there, but that shouldnt be much of a problem, as long as the pH of the solution is basic.
The production of hydrazinium sulphate is taken out of a well-known preparative anorganic chemistry book, 'Lehrbuch der analytischen und
praeparativen anorganischen Chemie (13th/14th edition)', by Jander & Blasius
REACTIONS:
NH3 + NaOCl --> NH2Cl + NaOH
NH3 + NaOH + NH2Cl --> NH2NH2 + NaCl + H2O
NH2NH2 + H2SO4 --> (N2H6)SO4 (precip
PREPARATION:
To an Erlenmeyer flask of 750 ml size, 165 ml of conc. ammonia solution is added (normally thats around 25%), + 35 ml water and in addition 15 ml of a
solution of scotch glue, gelatine or EDTA (2 g of any of them suffice ---- this is added to avoid heavy metal-catalysed reactions such as 2NH2Cl +
N2H4 --> 2 NH4Cl + N2 (gas)).
For making the NaOCl solution, Cl2 is bubbled through 100ml of 2 M NaOH while cooling on ice, until the weight has increased by 6 grams! (couldnt be
easier!!). This is less than the stoichiometric amount, as the solution ought to be alkaline, and entirely devoid of free Cl2!!!!
This solution of NaOCl is then poured into the ammonia solution (see above), and the resulting mixture is rapidly heated to boiling and reduced to
half of the original volume by evaporation (around 150 ml). Then the solution is first cooled with water, then ice; then concentrated H2SO4 is slowly
added until no further precipitation ensues.
The crude product is recrystallised with as small an amount of water as possible!
Melting point: 254 deg C (decomposition)
Free N2H6 can be obtained by mixing with stoichiometric amounts of NaOH, plus a bit of water, depending on the conc. you require.
Now comon, this can't be that hard?!?
In fact, I will be trying this within the next week or so, will post results as so many pple seem to have problems making it.
By the way - Polverone mentioned a method with acetone... here is a bit more detail :
About 1.5 mol/l NaOCl, Acetone, and NH3 are mixed with the molar ratios of 1:2:20. The solution then contains (apart from NaCl and NH3), acetonazin,
which is a very interesting compound (CH3)2C=N-N=(CH3)2 (figure out the reaction yourself!). This is destilled (after getting rid of the NH3 first by
heat/destillation) as an azeotrope with water.
The acetonazin is then decomposed by pressure destillation at 10 bar, and is collected as the 100% hydrazin hydrate (containing 64% N2H4). So maybe
not quite the method for the homechemist .... but I am already trying to
think of the fun things that could be done with acetonazin
[Edited on 21-11-2003 by chemoleo]
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Iv4
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How about adding ammonium nitrate to form hydrazine nitrate?Just my ignorence but would hydrzaine nitrate and ammonium sulphate form hydrazine
sulphate?
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