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Author: Subject: Making alcohol solutions of hydrazine.
Triflic Acid
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[*] posted on 1-7-2021 at 20:24
Making alcohol solutions of hydrazine.


I need an alcoholic solution of freebase hydrazine, and I have hydrazine sulfate. How should I go about making the solution? I don't want to have to vacuum distill the hydrazine.



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macckone
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[*] posted on 1-7-2021 at 20:36


Add calcium hydroxide or sodium hydroxide.
Both calcium and sodium sulfate are insoluble in ethanol and isopropanol.
Sodium bisulfate disproportionates to sodium sulfate and sulfuric acid in alcohols.
Don't use methanol if trace sodium sulfate is a problem.
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[*] posted on 2-7-2021 at 04:39


But isn't hydrazine sulfate also insoluble in ethanol/isopropanol? So how do I get the sodium hydroxide in ethanol solution to react with the sulfate?



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[*] posted on 2-7-2021 at 10:57


They will react unless your solution and your reagents are bone dry.
Mix them intimately and then add the ethanol if you are using calcium hydroxide.
If you are using sodium hydroxide, mix it with the alcohol then add the hydrazine sulfate.
Two phase reactions are a thing.
Same with isopropanol, except you are going to have to add both in stages as there are solubility issues.
One of the sodium azide preps uses isopropanol, sodium hydroxide and hydrazine sulfate.
Sodium sulfate will absorb any water present.
It also gets quite hot so good ventilation is absolutely mandatory.
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[*] posted on 2-7-2021 at 13:35


It seems more likely to be less convenient than that. IIRC the original preparation of anhydrous hydrazine was the methanolic HCl + sodium methoxide.



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[*] posted on 2-7-2021 at 14:20


The HCl is not very soluble either.
In methanol it is about 0.2g/100ml.
It is worse in ethanol and isopropanol.

The one that I know works right is sodium hydroxide in alcohol and add the hydrazine salt.
The calcium method, like everything involving calcium would be a pain the butt to filter.
Any biphasic reaction is going to require a lot of time and stirring.
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[*] posted on 2-7-2021 at 14:37


Weird how no one else seems to have heard the news.



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[*] posted on 2-7-2021 at 15:05


What do you mean?



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[*] posted on 2-7-2021 at 17:35


Where has hydrazine sulfate been used in this way in the past 130 years?

If something is insoluble in alcohol, that doesn't rule out solublility in alcoholic hydroxide, but how is the sulfate going to dissolve if sodium sulfate is also insoluble? Perhaps some hydrate could be made in water with an equimolar amount of hydroxide and the sulfate precipitated with alcohol and most water removed as the azeotrope, but it seems unlikely that the expected amount of sulfate or hydrate will be found.

What is the solubility of the hydrochloride in hot alcohols? More than the sulfate.




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[*] posted on 2-7-2021 at 22:02


Quote: Originally posted by macckone  
The HCl is not very soluble either.
In methanol it is about 0.2g/100ml.
It is worse in ethanol and isopropanol.


????

https://en.wikipedia.org/wiki/Hydrogen_chloride

Solubility of HCl in MeOH 47 g/100 ml, which is more than in ethanol and isopropanol (MeOH is more polar so just from logic it dissolve more HCl than longer chain alcohols).




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[*] posted on 3-7-2021 at 04:45


No Bedlasky, they are talking about hydrazine hydrochloride not hydrogen chloride!

If you convert hydrazine hydrogen sulphate (the normal stuff called hydrazine sulphate to the dihydrazine sulphate it is very soluble in water and ethanolic hydrazine solution can then be produced by carefully adding sufficient ethanolic sodium hydroxide solution. The resulting solution is not super strong and will contain a little sodium sulphate and water but it depend what you want to do with it. If you want anhydrous hydrazine in anhydrous ethanol I have posted details before on SM; try the search engine.
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[*] posted on 3-7-2021 at 05:45


The usual problem seems to be that there is still leftover hydroxide in the freebased hydrazine solution.

How do you get rid of that other than by destillation?
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[*] posted on 3-7-2021 at 06:17


^bubble CO2? AFAIK hydrazinium carbonates are not stable and will decomp to the freebase.



[Edited on 04-20-1969 by clearly_not_atara]
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[*] posted on 3-7-2021 at 09:27


Well, I seem to have found a prep:
Quote:

Anhydrous hydrazine is more easily prepared by adding a solution of sodium methoxide in methyl alcohol to a solution of hydrazine hydrochloride in, methyl alcohol. Sodium chloride produced is filtered off

I don't need anhydrous, so I'm going to use NaOH instead of NaOCH3. Also, anyone know a quick way of evaporating hydrazine hydrochloride solution, since I'm going to be making it by reacting calcium sulfate with hydrazine sulfate.

[Edited on 3-7-2021 by Triflic Acid]




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[*] posted on 3-7-2021 at 21:21


I assume you mean calcium chloride with hydrazine sulfate.
Filtering calcium sulfate is a pain in the butt.

Anything quick with hydrazine is going to be dangerous.
This is not something you want airborne even in salt form.
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[*] posted on 3-7-2021 at 21:58


S.C. Wack
The hydrazine sulfate solubility in ethanol is 0.04g/100ml.
I could not find good figures for both the sulfate and hydrochloride in both solvents.
Again hydrazine salts are not tremendously soluble.

I can tell you that sodium hydroxide dissolves just fine in alcohol.

Calcium hydroxide does not but it is more soluble than the sulfate.
Biphasic reactions are usually slow and require a lot of stirring and sometimes a PTC.

The best example of this is nurdrage's sodium synthesis.
It uses sodium hydroxide and magnesium in mineral oil with methanol as a PTC.

In the hydrazine salt case, with sodium hydroxide, it is soluble so you don't need a PTC as it is direct contact with the material, you just need stirring to expose 'fresh' material.
In the calcium hydroxide case, you are going to need a lot more time and stirring but there is some solubility without a PTC. If you start with a good mixture of powders, you don't need nearly as much time.
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[*] posted on 10-7-2021 at 07:16


Wait. Doesn't nurdrage produce freebase hydrazine in this video: https://www.youtube.com/watch?v=58Ve69s0qD0&ab_channel=N...



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[*] posted on 10-7-2021 at 09:15


No, he's making hydrazine acetate.

If you need it really clean then you will probably need to distill it. What do you want to do with it? For some usages the contamination may not be a problem.
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[*] posted on 15-7-2021 at 11:03


This might work if you have a feasible way of making large-ish amounts of liquid ammonia, or if you only need a small amount of hydrazine.


Quote:

In the treatment of hydrazine sulfates with liquid ammonia at about 33 C., i. e., the boiling point of liquid NI-la, the reaction products are free hydrazine and an ammonia addition product or complex known as the triammonate of ammonium sulfate. With the acid sulfate it is formed according to the following equation:


From patent US2680673A

Letting it warm up removes the ammonia(or, if you are really stingy about ammonia, you can add a gas adapter and recycle it for another batch or dissolve it into water.) Anyway, after that, adding some ethanol to the mix will dissolve out only the freebase hydrazine with very little byproduct. The ammonium sulfate isn't soluble in ethanol either, according to the patent.




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[*] posted on 17-7-2021 at 04:34


If you need larhe amounts of ethanoic hydrazine, distill it.
Although it is toxic, working with large amounts of liquid ammonia is going to be toxic as well.
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[*] posted on 18-7-2021 at 13:28


I'm going to need only a few grams worth, so this should work for me.



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