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Author: Subject: Benzaldehyde synthesis using aqueous nitric acid
Fyndium
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[*] posted on 17-11-2020 at 06:01


Wait a minute. There are two sources that state BzH has -26(Sigma, Britannica) or -54C(wiki, chem sites) mp. If -26 is correct, my solid could be it instead of an impurity. My freezer goes down -35 at best.

Btw, how quickly BzH oxidizes when handling, like separating layers, pouring into flasks, etc? Is the oxidation much slower at cold temps as it is fast in hot temps?

And finally, just as in persulfate method, could BzH be steam distilled directly from the reaction vessel or would HNO3 and other stuff co-distill?

EDIT: Prepared another test run, from 25mL BnOH I got 22g of BzH.

[Edited on 17-11-2020 by Fyndium]
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Fyndium
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[*] posted on 18-11-2020 at 05:32


This article appears interesting:

https://doi.org/10.1039/JR9600003932

It studies pyrolysis of benzyl nitrite alone, with BzH and various other stuff. There appears to be many references that BnONO is vacuum distilled, and it decomposes to nitrous or nitric oxide and CO2, BzH and other stuff, and decomposition half-life for ex in 190C vapor phase is 70min. Hence there appears to be of no danger of sudden explosions with this process.

If someone else notices potential issues, please refer. I thought that I could first vacuum a small amount and see how it behaves, and put some paraffin in the reaction flask to prevent going dry.
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Fyndium
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[*] posted on 19-11-2020 at 06:32


I successfully vac'ed the BzH. I got total yield of pure distillate from crude synthesis product in a bit over 80% yield, but I did not use fractioning column and I stopped the distilling when the temperature started to rise significantly. I collected most at 54C, where it climbed quickly and stayed most of the run, then it creeped to 60 and I stopped. Meanwhile the boiler temp was constantly 5C higher, but upon depletion it started to create larger margin and ended up to all the way to 80C.

It has a slight yellow tint, but whatever causes it, contaminates everything in trace amounts. A bucket of washing water with traces of yellow in ground joints turns all the water to pale yellow. Sodium percarbonate seems to intensify the color largely.
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