Sciencemadness Discussion Board

alternative oxidizers for hydrazine production

Polverone - 30-12-2002 at 17:53

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?

Nick F - 31-12-2002 at 05:03

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.

kingspaz - 31-12-2002 at 06:11

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?

vulture - 1-1-2003 at 05:59

Wouldn't that simply be ammonia? I would think NaClO would be banned for use in toilets if it actually produces hydrazine.

Microtek - 1-1-2003 at 07:09

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...


Polverone - 1-1-2003 at 13:58

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.

Microtek - 2-1-2003 at 02:50

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 ).

Polverone - 2-1-2003 at 14:36

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...

Microtek - 3-1-2003 at 04:12

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.

Nick F - 3-1-2003 at 05:23

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 :D:D
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.

you raise my hopes

Polverone - 3-1-2003 at 22:02

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).

Nick F - 4-1-2003 at 03:15

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...

Polverone - 5-1-2003 at 14:39

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.

Nick F - 5-1-2003 at 15:56

"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...

osamafon - 7-1-2003 at 04:53

1mol. urea+1mol.NaClO=N2H4


fluffy bunny - 11-1-2003 at 00:43

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.

Madog - 24-4-2003 at 13:48

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.


Theoretic - 17-11-2003 at 07:38

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.

A good effort but..

chloric1 - 17-11-2003 at 16:50

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.:D

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]

madscientist - 17-11-2003 at 21:34

The reaction Theoretic posted works when performed in aqueous solution - I've tried it.

Theoretic - 18-11-2003 at 08:26

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 - :D:D) 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.
"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 - :D)?
Have fun!

Iv4 - 19-11-2003 at 00:30

Not much but it all I could find.Couldnt the hydrazine be distilied of or something?

Theoretic - 19-11-2003 at 07:47

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. :D:D:D 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 :D:D.
"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.

Hydrazine sulphate

chemoleo - 19-11-2003 at 17:51

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

NH3 + NaOCl --> NH2Cl + NaOH
NH3 + NaOH + NH2Cl --> NH2NH2 + NaCl + H2O
NH2NH2 + H2SO4 --> (N2H6)SO4 (precip

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 :cool: .... but I am already trying to think of the fun things that could be done with acetonazin :D

[Edited on 21-11-2003 by chemoleo]

Iv4 - 19-11-2003 at 21:59

How about adding ammonium nitrate to form hydrazine nitrate?Just my ignorence but would hydrzaine nitrate and ammonium sulphate form hydrazine sulphate?

Al Koholic - 19-11-2003 at 22:09

To form hydrazine nitrate you'd really need nitric acid...

Starting with hydrazine sulfate yes I suppose based on the dissociation constants you could theoretically (if the hydrazine nitrate is less soluble in water than hydrazine sulfate which it might very well be based on anion stability) ppt hydrazine nitrate while leaving ammonium sulfate in solution. This would be a poor way of conducting the production though. Much easier to put the free base into solution and then acidify with nitric acid.

Ammonium nitrate and freebase hydrazine would be basically impossible to get hydrazine nitrate from.

Iv4 - 20-11-2003 at 02:47

I'm thinking about the hydrate then?

free base

chloric1 - 20-11-2003 at 08:04

Hydrazine can simply be liberated from the sulfate in liquid anhydrous ammonia because ammonium sulfate is insoluble in the latter. THe difficulty is in handling the anhydrous ammonia as it boils at -30C.:o

[Edited on 11/20/2003 by chloric1]

[Edited on 11/20/2003 by chloric1]

Iv4 - 21-11-2003 at 02:48

Bubled through it maybe?

If ammonium nitrate and hydrazine dont form hydrazine nitrate whats is the fuel astrloite really?Not being prick just curious.

KABOOOM(pyrojustforfun) - 25-11-2003 at 20:35

<blockquote>quote:<hr>(N2H5)2SO4 + Ca(OH)2 => CaSO4*2H2O + 2N2H4.
(N2H5)2SO4 + CaO => CaSO4*H2O + 2N2H4 <hr></blockquote>
the insoluble sulfate isn't (N<sub>2</sub>H<sub>5</sub>;)<sub>2</sub>SO<sub>4</sub> it's N<sub>2</sub>H<sub>5</sub>HSO<sub>4</sub> also the reaction with CaO is veeeeery exothermic making the hydrazine decompose in situ :D
to get HN from HS just mix a boiling HS sol with barium/calcium nitrate sol => filter. I don't know anythin about the solublity of HN in alcohol but have the feeling it dissolves, if so, one can use almost any metal nitrate, boiling most of the water away after mixing the sols => sinking the crystals in alcohol => filteration => evaporation => ready for *x***sion :D

Chris The Great - 22-9-2005 at 17:30

Tested a preparation of hydrazine sulfate using TCCA and urea. It was extremely easy and fast, however I am unsure if what I has is actually hydrazine sulfate and not something else (cyanuric acid?). My scale is not very accurate and so the amounts were probably off by a fair amount...

The general reaction should be something like this:
(ClNCO)3 + H2O --> (HNCO)3 + 3HOCl
3HOCl + 3NH2CONH2 --> 3N2H4 + 3HCl + 3CO2
3N2H4 + 3H2SO4 --> 3N2H6SO4

Approximately 18g of urea was dissolved into 100mL of distilled water. Approximately 20g of TCCA was added to a fair amount of distilled water. Not much dissolved despite my stirring. Then, 25g of sodium hydroxide was added, causing some foaming that immediately vanished when I started stirring again in a hurry (local overheating I think). Nearly all of the TCCA dissolved, leaving some chunks. I decided to add another 10g of NaOH since I think it had absorbed some moisture, and wouldn't be enough to take up the HCl generated. Once this was added all the TCCA dissolved leaving a solution the colour of milk. It cleared up when some more distilled water was added, leaving a warm, clear, yellowish solution.
The solution of urea was slowly poured in while rapidly stirring, giving off the expected rapid foaming. The mixture would foam up vigourously and then die down after approximately a second, and then more urea solution was added. The foaming stopped after about half the urea solution was added, but the rest was added anyway although more rapidly. The solution was still clear but was less yellow at this point.
A hot solution of 25mL distilled water and 20mL conc. sulfuric acid (I didn't bother to wait for it to cool, I just didn't want it to release all the heat rapidly in my hydrazine solution) was added, which caused more foaming (???). No precipitate was noted at this point, but a very fine amount formed as the solution cooled slightly (it was very hot by this point, probably >80*C). I put a lid on it and stuck it under the hose to cool it, this gave me a layer of white, very slightly grey precipitate, although the solution was still warm.
It's now sitting on my lab bench to cool down completely before I filter out my (hopefully) hydrazine sulfate.

If it is hydrazine sulfate, I'll try to optimize the procedure, I think using hot water for the TCCA/NaOH solution will help reduce the volume of water needed to dissolve them. I don't think NH3 would work as well because it is pretty hot, although presumably it can be done at lower temperatures the low solubility of TCCA will bring us back to the problem of having to use large volumes of dilute solution.
I think that an optimized procedure could easily give 400g hydrazine sulfate using a 4L pickle jar :D

Now, I do have a question- since no-one seems to have tried this method before, I'm not exactly sure what I have is hydrazine sulfate. It could merely be cyanuric acid or something. Is there some easy, simple, OTC test to see if what I have is hydrazine sulfate?

I have some high hopes for this procedure, I found it very simple and had no problems at all. Hopefully none will crop up when it is scaled up.

The_Davster - 22-9-2005 at 17:35

If you are to react your hydrazine with NaOH to form the hydrate, the hydrate should react with Silver nitrate to form a silver mirror. Other metal salts should work as well as hydrazine is such a powerfull reducing agent.

Chris The Great - 23-9-2005 at 19:36

I did a quick test using iodine tincture (didn't have anything else on hand), and sure enough after a faily vigorous reaction with NaOH, an alcohol solution of what was presumably a small amount of hydrazine hydrate caused the strong I2 colour to immediatly vanish.


Unfortunetly, I was unable to scale up the reaction. I have found out the hard way that TCCA readily decomposes into very irratating, very strong smelling gases when heated. I was using hot water to dissolve it to increase the solubility, and was rewarded with something that burns my respiratory tract like chlorine, has a very different and much more penetrating odour, and burns my eyes like hot ammonia.
I suspect this is some oxy-acid of chlorine or chlorine oxide of some sort, but cannot figure out exactly what it would be...

In this case I used 200g TCCA, 750mL of hot water. Decomposition set in soon after mixing, but stopped when cold water was added. It started again and wouldn't stop when I started adding NaOH.
I tried again, using cold water, and was rewarded with a more controllable problem- as long as I kept stirring it didn't seem to decompose, but as soon as I stopped it sat quietly for a few seconds and then started bubbling like crazy. It seemed to be energetic, as it increased in speed as time went on.

I do not know what this chemical could be, I am betting HOCl gas, but apparently that only exists in solution.

I think this is because of the strong heating caused by the addition of NaOH.

I therefore propose two possible actions:
-Use highly concentrated NaOH solution to greatly reduce the heating
-Add all the NaOH at once to prevent the TCCA from decomposing much in the first place
I would like to hear others thoughts before I continue however, the smell was highly unpleasant and being unable to breath while having your eyes tear and burn is not something I wish to repeat. I still think this method has possibility, but has some annoying problems that need to be worked out.

12AX7 - 23-9-2005 at 20:00

Well, first of all you have to prepare a basic TCCA solution, which means 1. NaOH + H2O = heat of dissolution; 2. TCCA + H2O apparently = heat of decomposition; and NaOH + TCCA chlorine = neutralization heat. Sounds to me like you should include some ice cubes in the next preparation. :)

I would recommend starting with an oh, 10 or 20% NaOH solution (remember, more water = more heat capacity!), cool it down, add TCCA and ice cubes and see where it goes.

BTW, can you start with urea sulfate and oxidize it to hydrazine sulfate?


Chris The Great - 23-10-2005 at 19:39

Well I tried a slightly different procedure, cold water and sodium bicarbonate as the base, hoping it wouldn't case the problems that NaOH had been causing.
Long story short, I ended up with the same painful gas being evolved, and when I added urea there was no foaming but chlorine was produced as well. So I don't think that this procedure will work very well, TCCA decomposes in the presence of a base seemingly, and the base is needed to take up the HCl generated or it will produce chlorine with the TCCA.
I think I will try adding urea and sodium bicarbonate in one solution over time to TCCA, but if that doesn't work...

However, I did have what will hopefully turn out to be a good idea. The problem I keep finding with TCCA is that it has a low solubility in water. However, it is very soluble in acetone, as is... ammonia!
So, I was thinking:
ClNCO (TCCA) + NH3 --> HNCO (cyanuric acid) + NH2Cl
NH2Cl + NH3 --> N2H4 + HCl
HCl + NH3 --> NH4Cl
Cyanuric acid and ammonium chloride are insoluble in acetone, and precipitate. Hydrazine is soluble and remains in solution. Insolubles are filtered out, acetone boiled off and anhydrous hydrazine remains.
Thoughts? I'll be trying it when I make some 30% anhydrous ammonia in acetone solution. A fair excess will be used as it seems excess ammonia leads to higher yields. Also, no heavy metal ions to screw things up.

I just have this feeling something will go wrong, like my other attempts at hydrazine using TCCA....

IPN - 24-10-2005 at 01:03

Hydrazine and acetone will react to form a ketazine, though that can be hydrolysed back to it's components. Also ammonia and acetone form some polymers + other odd things.. So I think acetone isn't the best solvent for your reaction.

[Edited on 24.10.2005 by IPN]

neutrino - 24-10-2005 at 02:18

I get the vague feeling that this might form NCl<sub>3</sub>. Being intimately mixed with a good reducing agent (the acetone), you might have a problem here. I’d suggest trying this on a test tube scale first.

On the other hand, the other reactions also seem like they would form some NCl<sub>3</sub>. Can anyone explain why they don’t?

Chris The Great - 24-10-2005 at 14:56

I think it's because there is always a large amount of ammonia, so that forming NCl3 isn't really favourable since it could just form 3 NH2Cl's.

As for the solvent, I will try acetone, see if it works, if not, I'll try some other solvents that TCCA is highly soluble in. The TCCA solubility seems to be the main problem with using it for making hydrazine, as it will be extremely dilute if dissolved into water which defeats the purpose, just use bleach in the normal method.

un0me2 - 4-8-2010 at 20:56

I'll post this because it is one of the better "theoretical" syntheses (that look legit) that I have seen, it uses NO gelatine, but does use Mn salts to make hydrazine sulfate from sodium hypochlorite and urea. The attached paper also details the liberation of the hydrazine hydrate & the dehydration thereof.

PS I quite like this book, who did I pinch it off?;) It has updated routes to a lot of very nice to have inorganic intermediates.

Attachment: Vorobyova.Practical.Inorganic.Chemistry.1987.pp.139.141.Hydrazine.Hydroxylamine.pdf (172kB)
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