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Author: Subject: Hydrazine
NurdRage
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[*] posted on 6-3-2011 at 17:11


OK good you're not pissed then. If you want respect, usually the best way to obtain it is to provide some. I'll forget everything that happened (cause actually, i honestly don't know WHAT happened) and continue on with what we're all really here for: actual chemistry :)

Using azines as synthons for hydrazine reactions sounds like an excellent idea. I'm personally not doing nitrite or azide chemistry, but i might apply it to synthesis of luminol.

I'm still thinking of possible synthetic routes to hydrazine through ketazine. I recall a paper that used air and a copper catalyst to oxidize the imine. It might be worth looking into since it removes the cost of oxidant, although i'm not sure what the exactly catalyst was or if it was easy to make. If its more expensive then obviously we'll need to consider other factors. I'll see what i can find.
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NurdRage
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[*] posted on 6-3-2011 at 21:47


I hope he was fired... for his own safety.

Consuming toxic stuff from the lab is Olympic level darwin award worthy.

EDIT: Wait... was it intentional? or did he just made a mistake? bronze medal darwin award worthy if that was the case.

[Edited on 7-3-2011 by NurdRage]
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[*] posted on 8-3-2011 at 11:29


Today I tried to make hydrazine sulfate following Nurdrages ketazine process.

The differences were that I used a little more reagents (300 ml 25% NH3, 484g approx. 4.5% NaClO soln. and 120 ml of MEK) and I used manual stirring (swirling in a flask).

After the ammonia and hypochlorite were cooled to around 0 C, I added the MEK to ammonia and started adding the hypochlorite, but only a little foaming was observed (so I finished adding all of the hypochlorite in a few minutes) and almost no ketazine formed.

To see what would happen if I added more NaClO, I poured 25 ml of the reaction mixture in a 100 ml measurnig cilinder and added around 30 ml of the NaClO soln. It started foaming moderatley and after a few seconds it went out of the cylinder (only a small amount tho). I then added again around 15 ml of hypochlorite solution which again caused foaming but not so strongly.

After trying that I added around 80-100 ml of hypochlorite solution to the main reaxtion mixture (the one in the flask). I started bubbling but not nearly as strong as in the cilynder. After a few seconds the bubbling stopped and would start again for a few seconds (but very weakly) if I swirled the flask.

I have left the flask to stand over night to see if some ketazine forms after all.

Perhaps my hypochlorite soln. was much weaker than I thought, but I doubt that because of the amount of foaming that I observed in the measuring cilynder.

All of the glassware used was washed with 19% HCl, then water and then distilled water to remove any potential metal-ion contamination.

Anyone have any idea what I did wrong?

PS: the smell formed during the reaction is very interesting, like a mix of ammonia, MEK, and something "sweet".

edit: I forgot to write that the NH3 and MEK were reagent grade, and the NaClO soln was bleach.

[Edited on 8-3-2011 by Zinc]




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NurdRage
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[*] posted on 8-3-2011 at 12:13


Foaming is a BAD sign actually, it means you're decomposing the hydrazine, i think you added too much hypochlorite. There was no need to go over stoichiometric amounts just because it didn't foam. Also, let the MEK react with ammonia longer, sounds to me you added the hypochlorite right after you added the MEK.

[Edited on 8-3-2011 by NurdRage]
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[*] posted on 8-3-2011 at 15:13


Indeed I added the hypochlorite cca. 1-2 min after the MEK.

I have a question about stirring. Is the highly efficient stirring absolutely required, or is the manual stirring (in my case swirling the RB flask) enough (if i get a little lower yield it is ok as I dont need a lot of hydrazine sulfate?
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NurdRage
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[*] posted on 8-3-2011 at 15:29


yeah i recommend waiting for at least ten minutes or so after adding the MEK. Most of the time i waited for 30 minutes.

I'm not certain about the stirring, maybe try stirring by hand with a stir rod instead, swirling the flask might not give adequate mixing.

Another concern is the bleach concentration. 4.5% might be too low that the final concentration of ammonia is no longer adequate for the reaction. Especially since it sounded like you added too much bleach, further diluting the reaction.

I'm not too confident about this last idea though since i was able to get it to work well with 6% bleach. I didn't over-dilute though.
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[*] posted on 10-3-2011 at 03:00


Today I tried the procedure again but with much smaller quantities.

I used 30 ml of 25% NH3, 12 ml MEK and 48 g of 4.5% NaOCl soln.

This time I let the MEK and NH3 react for 15 min, with often vigorous shaking in an erlenmayer flask. When I added the hypochlorite the temp rose (it became warm to touch, but not much, and my hands were cold), and not too much foaming was observed. Again no ketazine formed.

It seems that my hypochlorite is too dilute, or perhaps contains some impurities that hinder the reaction, altogh I doubt that as it looks like pure NaOCl soln. (green with a chlorine smell, on the bottle it says that it contains NaOCl and NaCl) and it is very cheap (around 1.2 dollars per l).
It is also possible that without magnetic stirring the MEK and NH3 should be left to react even longer, as I noticed that when they are mixed the MEK forms a seperate layer wich in time diminishes (by the time I added the NaOCl it was mostly gone, only some drops were visible).

Of course all the glassware was washed with HCl, water and distilled water.
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[*] posted on 10-3-2011 at 07:52


When i did my experiments with acetone, it wouldn't phase separate so i extracted with toluene.
Maybe you could try a toluene extraction, then obtain the hydrazine sulfate by reaction with dilute sulfuric acid.
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[*] posted on 10-3-2011 at 09:12


I did antoher try, this time with 15 ml 25% NH3, 6 ml MEK and 24 ml NaOCl, and let the NH3 and MEK react for around 1.5 h. They were in a measuring cilynder, so that I could observe how much of the MEK mixed with the NH3, after the sitting-time (with frequent shaking) 1-1.5 ml of MEK didn't dissolve. Adding the hypochlorite formed no ketazine.

I belive a good thing to try would be to make my own NaOCl (from p.a. grade NaOH to ensure purity) and try with that, but I don't yet have all the equipment needed to make Cl.

The toluene extraction is a good Idea, I could try that.
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[*] posted on 10-3-2011 at 09:33


how long after you added the hypochlorite did you wait?

Ya said some MEK didn't dissolve, was it still undissolved after you added the hypochlorite?
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[*] posted on 10-3-2011 at 10:40


The last time I waited around 1-1.5 h, the mix was clear, no turbidity like it would be expected from a dispersion. The attempt from yesterday stood over night, with the same result.

When I added the hypochlorite most of the MEK was dissolved. In the last attempt that I did in a measturing cylinder, from 6 ml of the MEK that was added, 1-1.5 ml was not dissolved. Almost all of the MEK dissolved within the first 15-20 min, after that only a very small amount dissolved.

When the hypochlorite was added all of the remaining MEK instantly dissolved in a completely clear solution.
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[*] posted on 10-3-2011 at 15:03


i'm outta ideas then. I guess stronger bleach and toluene extraction are the only options left.

I don't know how much it'll help, but have ya tried dissolving some gelatin into the ammonia before adding the rest of the ingredients? it'll precipitate somewhat when things get going but it might help a little.

The only other thing i can think of is to "salt out" the ketazine with sodium hydroxide. This needs to be done outside or in a fumehood as its going to belch out ammonia gas. Not the best option in my opinion since it wastes a tremendous amount of sodium hydroxide. Might as well go with the urea-hypochlorite method.

Ah well, if you do get it to work, or more importantly, if you don't, let us know. :)
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[*] posted on 11-3-2011 at 03:43


Yesterday I made a batch with 17 ml of NH3, 7 ml of MEK and 26 g of NaOCl soln. and let it stay over night.

Today I added 20 ml of toluene to the mix, swirled it to suspend the toluene, when the toluene separated I again swirled it to suspend it. When it again separated I removed the toluene layer into a flask and added a mix of 5 ml conc. H2SO4 and 7 ml of distilled water (the H2SO4 was added while still hot from the dilution). Upon adding the acid and swirling for a second or two, white powder precipitated (almost all of it in the H2SO4 layer, which was the bottom layer). There was no orange-colouring of the liquids. It seems to have worked :D:D

Now I have all of the remaining attempts (including the large one with excess hypochlorite, some extra water is also in the flask) mixed in a flask. I would be very good if the ketazine is still in that mix, and could be converted to hydrazine sulfate.
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[*] posted on 11-3-2011 at 07:35


Ah, so it was just merely a recovery problem due to high dilution, not a reaction problem.

Good thing the toluene can be recycled, it'll take awhile but you can recover a great deal of ketazine with that approach.

Nice work!

If i may ask, have ya tried the urea-hypochlorite process?
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[*] posted on 11-3-2011 at 07:55


I tested the mixture of batches, and indeed there was ketazine in it. I devided it into three portions, and each was extracted two times with toluene (first time fresh, the second time recycled. I can't remember how much toluene I used, it was all in all 200 or 250 ml. With those larger amounts the orange collor appeared when hydrolising with H2SO4.

The yield of hydrazine sulfate is not good (it is still drying, and I currently don't have access to a precise scale so I can't weigh it but it is around 6-10 g I belive) but that could be because of the long time the ketazine was standing in the solution (with some exess hypochlorite and water), and the flask in which it stood was only covered with a petri dish, so it wasn't airtight (that would only be a reason if the ketazine is air-sensitive). There probably is some still in solution, but I doubt that there is much as there was much less hydrazine sulfate formed from the second extraction than from the first. There is a posibility that my both of extractions partially failed and that there is still much ketazine in solution but I doubt that.

I am wondering what prevented the ketazine from separating from the solution in the first place, was it the dilution caused by diluted hypochlorite?

Anyway it was interesting to experiment with this, if I attempt this again i should definitley use more concentrated hypochlorite.

No I didin't try the urea-hypochlorite method yet.
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[*] posted on 11-3-2011 at 16:11


To be honest i don't really know. The excess hypochlorite might have killed the hydrazine. the dilution might have dissolved the rest.

Maybe you'll need some gelatin dissolved in the ammonia first to reduce the effect of impurities.

At least you got something out of it.

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[*] posted on 14-3-2011 at 00:02


After hydrolysis of ketazine with HCl, I would have solution of hydrazine hypochlorite. Could I add some copper, sodium or some other sulfate to precipitate hydrazine?
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[*] posted on 14-3-2011 at 06:15


Yesterday I weighed the hydrazine sulphate, and there is 18 g, much more than expected :D It seems that my visual determination of quantity is not very good:P
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[*] posted on 14-3-2011 at 06:38


@Random Try it and let us know the results, i never tried it myself.

@zinc so what would that be in terms of yield?
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[*] posted on 14-3-2011 at 07:21


Has anyone tried this with ice cold NaOH saturated solution and TCCA? Or making a concentrated NaOCl solution thusly?
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[*] posted on 14-3-2011 at 15:55


Fail, if I calculated it correctly that would be cca. 160% yield (based on NaOCl), impossible.
I am sure that the weight was correct (used a scale of 0.1g resolution). It is possible that the hydrazine sulfate was not completely dry as it was somewhat clumpy but still it couldn't contain that much water (it was dried for around 30-40 h, and the humidity was not too high, also as far as I know hydrazine sulfate is not hygroscopic). Is it possbile that some ammonia was extracted in the toluene (I did notice that the toluene extract smelled somewhat of ammonia, but I didn't think that much of it was in there, should have try to find out how soluble is NH3 in toluene) and formed the sulfate, which due to cooling (I cooled it to around 0 C before filtering it) precipitated along the hydrazine sulfate? Someohw I doubt that as ammonium sulfate is quite soluble in water (around 70g in 100 ml of water at 0 C) but perhaps because of the presence of sulfuric acid and hydrazine sulfate it's solubility was vastly reduced?
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[*] posted on 15-3-2011 at 05:46


Your yield sounds low, not too high.

since you combined all reaction mixtures then lets assumed you started with the original 484g of 4.5% hypochlorite. That's 21.78g of equivalent NaOCl, this is around 0.2926 mole, if there is perfect conversion to hydrazine sulfate then we get 38g.

or about 47% yield at 18g.

Since you performed additional reactions the actual yield is probably even lower.

Maybe my math is wrong,
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[*] posted on 15-3-2011 at 06:23


Actualy I failed in my calculations, I calculated how much pure hydrazine should I get, not how much sulfate and I compared the number for pure hydrazine with the amount of the sulfate I had (quite a stupid mistake indeed, should not do such stuff 1h after midnight).

I used in total 582g of 4.5 % NaOCl, that is 26.19g, or around 0.35 mole, so if the yield was 100% I would get around 45.6g of hydrazine sulfate wich makes my yield around 39 %.
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[*] posted on 15-3-2011 at 06:36


thats actually really good considering low concentration bleach was used and a few mistakes were made. Testament to how robust the process is.

What are you going to be using the hydrazine sulfate for?

EDIT: as for the original issue of why it never phase separated, another issue i just remembered is that sometimes MEK has acetone mixed in. Acetone azine is soluble in water. now I know you said your MEK was reagent grade so this is probably nt the issue.

[Edited on 15-3-2011 by NurdRage]
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[*] posted on 15-3-2011 at 08:05


Quote: Originally posted by NurdRage  
thats actually really good considering low concentration bleach was used and a few mistakes were made. Testament to how robust the process is.


Indeed, and that makes it very suitable for the amateur chemist who doesnt have always access to precise scales, more complicated equipment, very pure reagents, etc.

I used the hydrazine sulfate to make a small amount of NaN3.

Yes the MEK is p.a. grade and contains max. 0.002% acetone.
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