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Author: Subject: Hydrazine sulfate and sodium sulfate separation
Glass mycologist
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[*] posted on 6-3-2021 at 23:42
Hydrazine sulfate and sodium sulfate separation


Hello,
I hope the subject hasn't been treated elsewhere but I swear I checked TFSE and got nothing.
Anyway I performed the hydrazine synthesis by rearrangement of urea and was able to make it work. I collected a first crop of hydrazine sulfate after acidification but when I pursued acid addition I ended up precipitating sodium sulfate as well. Now that it's complete I separated the mother liquor from the crystals.
Do you think that recrystallization from water can help me separate sodium from hydrazine sulfate? If not I'm open for suggestions but I'd rather do it again than work with freebase hydrazine.
Can the mother liquor be boiled off to recover more product ?
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Bedlasky
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[*] posted on 7-3-2021 at 00:57


Are you sure that sodium sulfate precipitates? After acidification more soluble sodium bisulfate is formed. So if sodium sulfate doesn't precipitate in alkaline solution, why would sodium bisulfate precipitate in acidic solution?



If you are interested in aqueous inorganic chemistry look at https://colourchem.wordpress.com/main-page/

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Glass mycologist
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[*] posted on 7-3-2021 at 04:47


Well i'm not sure of what really precipitated but it looked like big transparent crystals, i'm not currently at the lab so i can't provide a picture but it looked very much like what google shows as sodium sulfate crystals (find the attached screenshot).

sodium sulfate.PNG - 143kB
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XeonTheMGPony
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[*] posted on 7-3-2021 at 05:59


This is where spending more research time would have saved you a large head ach!

Do the fist Neutralization with HCL then the final stage with H2SO4
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UC235
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[*] posted on 7-3-2021 at 05:59


As far as I know, hydrazine sulfate doesn't ever form large or transparent crystals, but if you're getting sodium sulfate decahydrate, you have not added nearly enough sulfuric acid. What's more, dihydrazinium sulfate formed by under-acidification is extremely soluble.
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Glass mycologist
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[*] posted on 7-3-2021 at 11:45


In fact the strange thing is that I observed white crystalline solid (much tinier crystals) along with the large crystals, I assumed the white solid was the desired hydrazine sulfate.
Should I try to continue the acid addition?

[Edited on 7-3-2021 by Glass mycologist]
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