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Belowzero
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Failure
Hello Sciencemadness,
It's been close to 10 years since I was active here and I am glad to see SM is going strong!
Anyway recently I got a new lab up and running and decided to synthesize a small batch of HS which seemed to have failed.
Since I had a hardcopy of this procedure and since it is similar to Rosco's method I gave it a go.
https://www.designer-drug.com/pte/12.162.180.114/dcd/chemist...
I used roughly 1/6th of the amounts used.
Which comes down to:
Urea 22.0g
Bleach 230.0ml 12.5 %
NaOH 32.3g
Pig Gelatine 0.3g
Sulfuric acid 183ml 37%
I didn't confirm the concentration of the bleach however I know this batch is relatively fresh and should be very near to 12.5%
This is 20ml less than the procedure to compensate for its higher concentration.
Now I know the neutralization step is suboptimal compared to the HCl route and took this for granted.
I might just have made very expensive glaubers salt because the procedure did not go as planned.
The dissolving of the NaOH was quite tedious, to buffer the temperature of the bleach I used a large cold water bath.
The temperature never rose above 10 degrees C.
After adding all the reactants a large evolution of gas was witnessed, the temperature rose strongly (no measurements)
almost too hot to touch the flask.
Expecting the foaming as described and seen in my earlier days of making this substance I was surprised hardly any foam was produced at all, only a
very small whiteish layer above the liquid. This subsided entirely after a few minutes.
The production of gas stopped entirely after an hour or so and I decided to kick up the heat to just below boiling.
More gas was produced and the heat was turned off again.
I called it quits because no distinct coloration nor foaming was witnessed and dumped the content in a large beaker in a cold water bath. The sulfuric
acid was added and left to cool in the same bath, ~10-15 degrees C.
The next day a layer of white precipitate was formed.
No tests have been conducted yet on the product.
I suspect I have made really expensive sodium sulfate.
Now the question is why didnt the reaction foam excessively like it should?
I suspect it is due to metal traces in the reaction , the groundwater contains quite some iron. I use this to wash my glassware.
Of course knowing this I took extra care and flushed it with both NaOH solution and HCl as an attempt to get rid of traces.
Looks like it still was not enough to get rid of it.
Or perhaps I messed something else up like using too much hypochlorite.
Any suggestions ?
[Edited on 25-5-2020 by Belowzero]
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woelen
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Did you test the white solid? Does it dissolve in cold water easily? If not, then it might be hydrazinium sulfate (that compound only dissolves with
difficulty in cold water). Another test for hydrazinium sulfate is to add this to an acidified solution of KMnO4. This will lead to nearly
instantaneous loss of color of the solution. If it is just sodium sulfate, then there will be no loss of color and if it is urea, then there will only
be slow disappearance of color.
You could also add some of the solid to a concentrated solution of an acidified chlorate, bromate or iodate. With hydrazinium sulfate you will have a
very violent reaction.
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Belowzero
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Quote: Originally posted by woelen  | Did you test the white solid? Does it dissolve in cold water easily? If not, then it might be hydrazinium sulfate (that compound only dissolves with
difficulty in cold water). Another test for hydrazinium sulfate is to add this to an acidified solution of KMnO4. This will lead to nearly
instantaneous loss of color of the solution. If it is just sodium sulfate, then there will be no loss of color and if it is urea, then there will only
be slow disappearance of color.
You could also add some of the solid to a concentrated solution of an acidified chlorate, bromate or iodate. With hydrazinium sulfate you will have a
very violent reaction. |
Thanks Woelen!
I conducted the test with KMnO4 , I dissolved a few crystals in 10 ml of water with a drop of H2SO4.
When I dropped in a few supposed HS crystals the solution went to light pink and then white almost instantly.
Also the material is poorly soluble in cold water, I attempted to dissolve a few wet crystals in 20ml which didnt go into the solution upon stirring.
The wet crystals are now washed ,vacuum filtered and put in a dessicator, I'll conduct more tests to rule out any false positives.
It seems the synthesis did produce HS after all.
I am still clueless as to why the foaming was practically absent, if the yield is good it might be worth investigating since the foaming is the worst
part of this procedure and it would be great if this could be prevented.
More results later.
[Edited on 26-5-2020 by Belowzero]
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B(a)P
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| Quote: Originally posted by Belowzero |
It seems the synthesis did produce HS after all.
I am still clueless as to why the foaming was practically absent, if the yield is good it might be worth investigating since the foaming is the worst
part of this procedure and it would be great if this could be prevented.
More results later.
[Edited on 26-5-2020 by Belowzero] |
The amount of foaming you get is very variable and depends on the additives in the bleach. I switched to pool chlorine for my HS thinking it would not
have many additives and it has a high NaClO concentration. However, it foams more than any other NaClO source that I have used before. It does produce
a good yield though.
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Belowzero
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| Quote: Originally posted by B(a)P | | Quote: Originally posted by Belowzero |
It seems the synthesis did produce HS after all.
I am still clueless as to why the foaming was practically absent, if the yield is good it might be worth investigating since the foaming is the worst
part of this procedure and it would be great if this could be prevented.
More results later.
[Edited on 26-5-2020 by Belowzero] |
The amount of foaming you get is very variable and depends on the additives in the bleach. I switched to pool chlorine for my HS thinking it would not
have many additives and it has a high NaClO concentration. However, it foams more than any other NaClO source that I have used before. It does produce
a good yield though. |
NaClO is actually the only thing it contains according to the label , I'll have another look at what the manufacturer mentions.
The precursors used are all quite pure in fact.
Externally introduced impurities is the only thing I can think of at this point.
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Fyndium
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I was about to bump an old topic, but noted that there is actually a major thread on this matter.
Hydrazine forms 68.5% azeotrope according to wiki ( https://en.wikipedia.org/wiki/Azeotrope_tables ) which would indicate that distilling it would proceed as with nitric acid.
https://www.prepchem.com/synthesis-of-hydrazine-hydrate/
This source depicts that it is practically done as said, but with very little water, apparently to gain over 90% concentration, and without vacuum, so
apparently at least vacuum is not necessary. I presume that adding more water to the azeotrope balance would yield to collection of azeotropic
hydrazine. They note that the major corrosive contributor is the hydroxide, not the hydrazine itself. The trouble of getting a copper/silver/tantalum
retort equals to ordering a dozen or two of 500-1000mL flasks from china, so a potential sacrificial flask would be a much better choice. Running
without vacuum could make things easier, as no active exhaust of hydrazine fumes happens, and it can just simply put behind a trap.
[Edited on 15-1-2021 by Fyndium]
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Jebby
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I followed the procedure from NileRed’s video scaled down by half. I tried to add the urea gelatin mix to the basic bleach solution all in one go
and it almost immediately started foaming uncontrollably spilling everywhere. The temperature of the bleach solution was around 8 to 10°C and the
gelatin+urea was still slightly warm. The bleach I am using is about 7% and I’m using tech grade NaOH drain cleaner. I’ve tried the reaction 3
times and had one run that gave me a few mg of hydrazine sulfate. I was wondering if anyone had any ideas as to what I’m doing wrong.
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clearly_not_atara
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I think you could make methyl carbazate via the reaction of hydroxyurea with dimethyl carbonate as described in the attached. Assuming that DMC
doesn't react with the other side of the hydroxyurea, it should be fine.
Hydroxyurea is itself produced by the rearrangement of hydroxylammonium cyanate produced by salt metathesis (hydroxylammonium X + M cyanate).
This adds up to a laborious but OTC and "clean" prep of hydrazine by hydrolysis of methyl carbazate. The Lossen has successfully been performed on
substituted hydroxyurea via carbonates as well, cf:
https://pubs.acs.org/doi/full/10.1021/acs.orglett.9b01742
Attachment: kreye2012.pdf (196kB)
This file has been downloaded 474 times
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clearly_not_atara
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Found this while looking up something unrelated:
https://pubs.acs.org/doi/abs/10.1021/ja01063a013
Oxidation of benzhydrylamine [...] in hot excess permanganate, benzophenone azine (VII) is formed.
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ManyInterests
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This thread is fascinating. I've been looking into various ways to make hydrazine sulfate, but I have one simple question:
When you use HCl to reduce the alkalinity of the solution before adding the 50% H2SO4, would hardware store muriatic acid suffice? I have some ro-tyme
muriatic acid at 31.25% concentration, but I am not sure about other possible impurities.
I bought a bottle of 10% Sodium hypochlorite pool chlorinator, but that was months ago. I hope it didn't degrade too much.
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ManyInterests
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So I have my first batch of hydrazine in the freezer that is around 20 or 21 c. I have one question: Does Hydrazine retain it's own heat so well? I've
never seen a substance take so long to cool down before.
Edit: No it's fine. It came out. It just took a lot longer than I thought. My freezer is also OK.
[Edited on 28-10-2021 by ManyInterests]
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Belowzero
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| Quote: Originally posted by ManyInterests | This thread is fascinating. I've been looking into various ways to make hydrazine sulfate, but I have one simple question:
When you use HCl to reduce the alkalinity of the solution before adding the 50% H2SO4, would hardware store muriatic acid suffice? I have some ro-tyme
muriatic acid at 31.25% concentration, but I am not sure about other possible impurities.
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One thing that comes to mind is that metal contaminants can be responsible for significantly lowering the yield.
Without knowing which impurities are present it is hard to say anything resonable here.
Perhaps you can boil down some of the stuff to see if it leave solids behind.
Basically any acid will do, iirc HCl(instead of H2SO4) is used to prevent other sulfates from coming out of solution.
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ManyInterests
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OK that is good. I was not aware of that.
BTW, I finally dried my yield, and I think it seems awfully high. I used 50% of the amounts used in this video:
https://youtu.be/K4p8zHuPVIM
But while I was expecting a similar yield of 20 grams or so, I got a yield of 29 grams. I am wondering if I have a lot of sodium sulfate contamination
in it. I did put it in the freezer and peroidically checked my glass thermometer until it hit around 13 or 14 c. It took an awful long time to cool
down, but It did. What could have happened for my yield to be so high?
Also if I may, can I draw your attention to another thread I made on disposing of the hydrazine and the byproducts of the synthesis in this thread. I
want to make sure I disposed of everything correctly.
https://www.sciencemadness.org/whisper/viewthread.php?tid=15...
Thanks.
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ManyInterests
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OK so I attempted to freebase some hydrazine... but I am pretty sure something was off. It is possible that my hydrazine sulfate was far too
contaminated with sodium sulfate. I added around 30 grams of sodium hydroxide gradually to 40 grams of hydrazine sulfate, with 110ml of ethanol added.
I mixed them for about 20 minutes and let them sit in an ice bath (covered with plastic wrap) for almost an hour now and the liquid is milky white
with no clear liquid out there. I added more ethanol and the ethanol solution is still very milky white.
Was my hydrazine sulfate a dude or what?
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B(a)P
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| Quote: Originally posted by ManyInterests | OK so I attempted to freebase some hydrazine... but I am pretty sure something was off. It is possible that my hydrazine sulfate was far too
contaminated with sodium sulfate. I added around 30 grams of sodium hydroxide gradually to 40 grams of hydrazine sulfate, with 110ml of ethanol added.
I mixed them for about 20 minutes and let them sit in an ice bath (covered with plastic wrap) for almost an hour now and the liquid is milky white
with no clear liquid out there. I added more ethanol and the ethanol solution is still very milky white.
Was my hydrazine sulfate a dude or what? |
Do you have any of your initial product left? There are tests you can do to identify hydrazine sulfate.
In my experience you sometimes need a little water to kick the reaction off. Were you using absolute ethanol or aziotropic?
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ManyInterests
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| Quote: | | Do you have any of your initial product left? There are tests you can do to identify hydrazine sulfate. |
I used 40 grams and I think I have about 20 grams left. I don't have much faith in them to extract enough hydrazine freebase in order to finish my NHN
synthesis. But I can test it if you like. I need to take a break from this for a bit before I do another synthesis of hydrazine. I have enough
experience with it so I can use the 'normal' quantities instead of half quantities.
I will be using hydrochloric acid in addition to sulfuric in making it. If that will free up more hydrazine sulfate. This failure was extremely
frustrating to me.
| Quote: | | In my experience you sometimes need a little water to kick the reaction off. |
When I opened my hydrazine container (I store it in a plastic tupperware) I noticed that the coffee filter I put under it was quite moist, so I assume
it was not 100% dry even if I thought it was. How much water are we talking about here?
| Quote: | | Were you using absolute ethanol or aziotropic? |
I used 95% denatured ethanol. Every guide I looked at in freebasing (including chemplayer, who I followed as closely as possible). I also have 99%
isopropyl alcohol to use if that will yield a better result.
I need to ask this one question about my failed NHN synthesis. While I do believe I made excellent nickel nitrate (it was very dry, no nitric acid,
and extremely green). When I added it to the rather... non-freebased hydrazine, the color turned green and some kind of green goo percipitated. I am
not sure what it is, but I don't think it's an explosive of any kind and I need to dispose of it. I poured 10% sodium hypochlorite solution and
calcium hypochlorite solution and it turned black. Did the left over liquid (which had hydrazine as evident when I poured the sodium hypochlorite in
it.
I also poured some bicarbonate solution in case there is any acid. What other precaution should I take before putting this stuff in the trash?
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B(a)P
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| Quote: Originally posted by ManyInterests | | Quote: | | Do you have any of your initial product left? There are tests you can do to identify hydrazine sulfate. |
I used 40 grams and I think I have about 20 grams left. I don't have much faith in them to extract enough hydrazine freebase in order to finish my NHN
synthesis. But I can test it if you like. I need to take a break from this for a bit before I do another synthesis of hydrazine. I have enough
experience with it so I can use the 'normal' quantities instead of half quantities.
I will be using hydrochloric acid in addition to sulfuric in making it. If that will free up more hydrazine sulfate. This failure was extremely
frustrating to me.
| Quote: | | In my experience you sometimes need a little water to kick the reaction off. |
When I opened my hydrazine container (I store it in a plastic tupperware) I noticed that the coffee filter I put under it was quite moist, so I assume
it was not 100% dry even if I thought it was. How much water are we talking about here?
| Quote: | | Were you using absolute ethanol or aziotropic? |
I used 95% denatured ethanol. Every guide I looked at in freebasing (including chemplayer, who I followed as closely as possible). I also have 99%
isopropyl alcohol to use if that will yield a better result.
I need to ask this one question about my failed NHN synthesis. While I do believe I made excellent nickel nitrate (it was very dry, no nitric acid,
and extremely green). When I added it to the rather... non-freebased hydrazine, the color turned green and some kind of green goo percipitated. I am
not sure what it is, but I don't think it's an explosive of any kind and I need to dispose of it. I poured 10% sodium hypochlorite solution and
calcium hypochlorite solution and it turned black. Did the left over liquid (which had hydrazine as evident when I poured the sodium hypochlorite in
it.
I also poured some bicarbonate solution in case there is any acid. What other precaution should I take before putting this stuff in the trash?
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Test your hydrazine sulfate, you can't freebase hydrazine if you don't have it in the first place.
The reaction for the liberation of hydrazine needs a little water to get it started because of the limited solubility of hydrazine sulfate in ethanol.
Once started the reaction generates water so no more is needed. It is a finicky reaction that requires close and careful observation. If there are no
signs of the reaction commencing after the first sodium hydroxide addition then there is not point in adding more until you can get the reaction
started. On the flip side if the reaction gets going to quickly/vigorously it will also fail.
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ManyInterests
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OK so I think the problem is that my synthesis went wrong somehow. I will go through the thread I commented on and pyrotechnical science's video again
(where he uses hydrochrloric acid. I think it was you in another thread that said that even the technical grade muratic acid is good enough for this
stuff. I want to extract good hydrazine sulfate. Just one good batch and I should have enough for a single NHN synthesis. At least my nickel nitrate
synthesis went good!
What test can I do to make sure I have hydrazine sulfate? I was told I jst need a test tube and a blowtorch. I don't have any test tubes and just a
barbique lighter.
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fredsci93
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One test for hydrazine is to heat the hydrazine sulfate with nitric acid to ~70C and pass the produced vapours through lead, copper or silver nitrate,
it should produce hydrogen azide fumes which will make the metal nitrate solution precipitate metal azides.
But I would not recommend this unless you can handle highly explosive and highly toxic gasses since hydrogen azide is very toxic and very explosive.
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B(a)P
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| Quote: Originally posted by ManyInterests | OK so I think the problem is that my synthesis went wrong somehow. I will go through the thread I commented on and pyrotechnical science's video again
(where he uses hydrochrloric acid. I think it was you in another thread that said that even the technical grade muratic acid is good enough for this
stuff. I want to extract good hydrazine sulfate. Just one good batch and I should have enough for a single NHN synthesis. At least my nickel nitrate
synthesis went good!
What test can I do to make sure I have hydrazine sulfate? I was told I jst need a test tube and a blowtorch. I don't have any test tubes and just a
barbique lighter. |
You can distinguish between sodium sulfate and hydrazine sulfate very easily by testing the melting point. Hydrazine sulfate has a much lower melting
point and will decompose with further heating.
A more specific test was mentioned above.
You can also react silver nitrate with hydrazine sulfate in a glass vessel to make a silver mirror, you would need to research the specifics of the
reaction.
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ManyInterests
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That sounds good. I have around 20 grams of sulfate remaining (but I seriously doubt it's purity). I will try test a bit of it. Maybe even try to
freebase it, but I won't hold my breath... or maybe I will, as breathing in any hydrazine fumes is no good! 
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ManyInterests
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My goodness! I think I figured out why my hydrazine sulfate synthesis went wrong before! No wonder I couldn't freebase any hydrazine. My first two
synths failed to synthesize anything other than sodium sulfate or whatever.
So what happened is when I put in the urea/gelatin solution I didn't wait for the thing to fully react, or it didn't react correctly before I turned
up the heat. This is the first problem. The second problem is that I avoided HCl, which probably affected the yield a lot.
That being said. This time I did my synthesis (It's cooling as I write this) and now I see the sulfate already forming like in all the videos I have
seen, and it isn't even 20 C yet. I will harvest the moment it hits 15C
the only thing I might have done wrong this time is let the temperature hit 20C for a brief bit, but it never went beyond that and it cooled to 19 C
and below in a minute or less.
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fredsci93
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That's good that you sorted the problem, hopefully the hydrazine freebasing will go better with the new source of hydrazine sulphate.
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ManyInterests
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Yeah. I should have noticed that I didn't get any sulfate precipitate like in the videos, but this time I got a lot of precipitate the moment I
finished adding the sulfuric acid. In fact I got no precipitate at all until the temperature dropped below 15... So that stuff was mostly, if not
entirely, sodium sulfate.
Now it looked like all the videos. I will wait 24 hours or so to let it dry at room temperature and try to squeeze out as much liquid as possible. I
did see pyrotechnical science dry his on a hot plate, but that sounds very excessive to me. A bit of hand squeezing with paper towels should be
sufficient.
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S.C. Wack
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| Quote: Originally posted by S.C. Wack | | Sauron seems to have deleted where he doubted making hydrazine from urea and hypochlorite, which makes my looking up DE164755, US1959503 (the above GB
patent), DE729105, and DE735321 seem pointless. |
The 1939 Inorganic Syntheses entry for hydrazine sulfate begins with "The only satisfactory method for synthesizing hydrazine was devised by Raschig
[1907] and involves the oxidation of ammonia by sodium hypochlorite in the presence of some such catalyst as glue or gelatin." They go on to say
"Although it has long been known that benzaldehyde reacts with hydrazine in alkaline solution to give a yellow, insoluble precipitate of
benzalazine and that the latter when steam distilled in the presence of mineral acids is hydrolyzed to give the corresponding hydrazine salts*,
no previous attempt has been made to apply these facts to the recovery of hydrazine residues.", their *citation being Zhurnal Russkago
Fiziko-Khimicheskago Obshchestva 37, 1 (1905) and its JCS abstract.
IS fails to mention that the cited Russian article (its title, ~ "The action of hypochlorites on urea: a new synthesis of hydrazine" is also unsaid)
is not about benzalazine but is in fact a synthesis of hydrazine from urea and 7.5% sodium hypochlorite in 60% yield, by way of benzalazine, and also
that the JCS abstract says nothing of benzalazine or much of anything at all. The IS authors must have read a better abstract at the least for that detail, and would have been aware of the yield, and certainly that benzaldehyde was applied to the recovery
of hydrazine. The use of benzaldehyde can't be unsatisfactory since IS employs it, and their yield from ammonia is 35%, based on hypochlorite.
Dr. Petr Ivanovič Šestakov (Czech? published from St. Petersburg) /P. J. Schestakoff/P. J. Schestakow (let's call him Shestakov in this language)
obtained DE and FR patents for the process in 1903, and he might have been frustrated by such treatment from these and other writers, if he survived
1905 (the 1905 revolution); I couldn't find any information about him. Hofmann and Raschig stole all his thunder; he gets only a little love for this
(mostly through Houben-Weyl) with the "Shestakov Rearrangement" of hydantoic acids to hydrazino acids.
The Chem. Centr. abstract says that without the benzaldehyde, Shestakov's yield was 20%; thus the benzaldehyde (and, "30-40 g of hydrazine sulfate can
be prepared from 1 liter of urine"). It's rather amazing that it took 25 years for someone to consider using Raschig's additives with Shestakov's
substrate; urea was dismissed by several experimenters before IS took things so far as to disappear it. US1959503, using urea with glue, gelatin, etc.
without benzaldehyde, was issued to Germans in 1932. (it is said that hydrazine was not produced in the USA until 1938, and then only for boiler water
treatment) Yield is still 60+%. Doubly ironically, it was Raschig GmbH (which still exists) who held the patent to a later additive for further
improving Shestakov's discovery, employing Mn, said years earlier to be detrimental to the Raschig method.
Beispiel
Zu einer Lösung von 74,5 g Natriumhypochlorit in 1000 ccm Wasser werden zunächst 280 g NaOH 45° Baume gegeben. Dann wird das Gemisch mit 15 ccm
einer 1/2 %igen Mangansulfatlösung versetzt. Nach Kühlung auf etwa 15° werden 60 g Harnstoff zugesetzt. Hierauf wird zum Kochen erhitzt und die
Lösung etwa 5 Minuten lang bei dieser Temperatur gehalten. Aus der Reaktionslösung kann man das Hydrazin in bekannter Weise als Sulfat oder als
Hydrat gewinnen. Die Ausbeute beträgt 78 bis 90 g Hydrazinsulfat = 60 bis 70% der Theorie.
Lately, I've been optimizing that for my hands, as I have some interest in hydrazine in organic chemistry. 70%+ yield has only been possible when the
yield is based on hypochlorite, and less than 1 mol. of it is added. The ceiling based on urea, using the cheapest 7.5% bleach, is 64%. 60% based on
urea should be considered a minimum, even though 56% would be higher than anyone's book, video, or internet recipe using gelatin.
Not overlooking hepatotoxic/genotoxic/carcinogenic/mutagenic hydrazine vapors or sulfate mist, a kitchen stove with 4 burners and large pots of water
can accomodate perhaps 16 loosely sealed Mason jars of quart size, yielding a kg of hydrazine sulfate, using 7.5% bleach and with acidification in 2
5-gallon buckets. The entire process to dry crystals can be performed in an hour if one is in a hurry (if washed with volatile solvent), and has
pre-cooled reagents.
Further regarding toxicity, anyone who says that there is a conspiracy to not cure cancer with hydrazine sulfate is a proven idiot, who is wet clay in
the hands of conspiracy theorists and shameless profiteers, plus either willfully ignorant of or hostile to over 120 years of science. Someone who
sells or advises using this to ingest obviously isn't taking it themselves.
Reproducible results are challenging when using different bottles of bleach, without titration. Bottles from the same grocery shelf can have obviously
different color and clarity. I suggest starting with a theoretical 10% deficiency of hypochlorite and 10% excess of NaOH, which appears to be the most
economical plan. If the yield is still not good with equimolar hypochlorite and excess NaOH, more bleach will not help because chloric acid and
chlorine will not help, and titration will probably indicate that the bottle has gone bad. A homemade hypochlorite with the amount of free NaOH
required for the process will store and yield better than any commercial product.
To produce 1.3 kg of the sulfate (500 g of the hydrate, theoretically), I'd need roughly 1 kg urea, 14 l "7.5%" bleach, 4 l conc. sulfuric acid, and
1.5 kg NaOH. So, it would not be an inexpensive mission. Stop reading here if you're uninterested in these experiences, because those concise six
sentences of patent are transformed even further to a long dull story of questionable value.
Elsewhere in the patent, they say that the form of Mn is not particularly important. The specified concentration is not randomly chosen. The solution
is completely decolorized after heating with their amount of Mn. It may be convenient to use this decolorization as the end point of heating, but I
prefer to double their amount, and this is not decolorized. Either way, the Mn precipitates and can be filtered after cooling, but it's not easy or
obviously beneficial.
Stirring is not mentioned in the example, which I suspect is not accidental. I also suspect that a flaw of other investigators using urea and gelatin
is employing stirring (and, maximizing hypochlorite concentration, and, adding solid NaOH to hypochlorite regardless of temperature, and, bad ratios).
Using considerably more NaOH, or less, is not necessarily detrimental to the yield of hydrazine or its sulfate, but then I'm not using M hypochlorite
(not deliberately at least), as the patent describes.
The overall concentration is perhaps similar however, as my urea is a solution (the eutectic), cooled as far as possible in a RBF (as is the bleach,
in a stoppered FBF) in the freezer, with the Mn solution and 42% NaOH stored in the fridge. This is out of habit, but the temperature does not seem
particularly critical, and in fact many aspects of all this can be varied without changing the yield much. The NaOH is prepared and kept in a plastic
container. First the bleach is added to it, and with some agitation, the Mn solution. This mixture is shaken hard and immediately dumped into the
urea. A drying tube packed with damp paper towel is added to absorb vapor. The RBF with drying tube is clamped and lowered into boiling water. There
are 2 separate stages with vigorous gas evolution, yet 85% of the volume of the reactor can be filled with liquid if desired. Much gas at both stages
(and probably also during acid addition) is a sign of not enough Mn and/or NaOH, too much hypochlorite, or bad hypochlorite.
After heating, the flask is chilled, then sulfuric acid from the freezer (1:2 v/v conc. acid/water) is added from a pressure-equalized addition funnel
topped with the drying tube from earlier, just until about neutral, with magnetic stirring. This requires 3 minutes, and caution while adding the last
25% of the acid. The liquid is transferred to a FBF of the same size and shake-swirled by hand to degas until the solution is cleared. The flask is a
bit warm to the touch. Half of the desired amount of conc. sulfuric acid is dumped in. When no more precipitation seems imminent, the other half is
added and the FBF is left to sit while loosely stoppered. When the flask no longer feels warm, the mixture is filtered with vacuum, with the RBF as
receiver. Once the crystals are sucked dry, they're washed twice in the filter with more of the cold 1:2 sulfuric acid, adding to the filtrate which
is then put in the fridge for a time. A second washing follows with 91% IPA, repeated twice. After cooling, a second crop of crystals are washed as
before. These crystals sparkle, but are less pure than the first. It's entirely possible to not use a filter at all, or to use a coffee filter. After
the crystals have digested some, they fuse a bit and can stick to the flask, even if the whole mass moves about. With enough care, the flask can be
inverted completely without any crystals coming out.
If the acid is added all at once, there is a tendency for the liquid to turn green (especially if warm), which is probably not a good thing. If there
is stirring after neutralization, a dull powdery snow falls, not sparkling in the light at all. This is full of Na even if precipitated warm. If one
intends to recrystallize anyways, go ahead and use magnetic stirring, but I prefer a fog turning to a rain of thousands of little sparkles which then
stick together to form shaved ice of good purity. There is no danger of sodium (bi)sulfate crystals if the hydrazine sulfate is mostly precipitated
before cooling below 30C, and the amount of acid is not excessive, although of course increasing the sulfate ion concentration also benefits the
precipitation of the hydrazine. A large excess of NaOH requires a large excess of acid, and when this acid is sulfuric, particularly good
precipitation of clean nicely crystalline product may occur, contrary to expectation that the increased Na in solution is an issue.
In other words, good yields are easy, but the highest yield requires some care.
It's possible that a more dilute solution works just as well, when water is removed after partial acidification, or more acid is added. It's also
possible that a more dilute hypochlorite gives better hydrazine yield; I haven't explored it, nor the use of lab grade chemicals.
Recrystallization leads to over 20% of the hydrazine sulfate remaining in solution at room temperature (10% if a modest amount of conc. sulfuric acid
is added after dissolving) so is best avoided. Obviously, good overall recovery may occur after some evaporation, if the amount of sodium
contamination is small. The pure sulfate leaves no nonvolatile residue when heated to decomposition in an evaporating dish with enough flame. In a
crucible or test tube, a S residue, etc. condenses on the walls. Weighing the residue left in an evaporating dish is faster than titration with
iodate.
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