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Author: Subject: Acetaldehyde synthesis
Magpie
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[*] posted on 12-3-2017 at 10:22




I had a suspicion that this was not a practical route to acetaldehyde. Usually practical routes can be readily found in published procedures.

Quote: Originally posted by byko3y  

I have no double the reaction is possible, but I have no idea how to perform it. The only thing I'm sure is that you can't get acetaldehyde by heating ethylene glycol in a dillute sulfuric acid.


I take it that you have tried it, then?




The single most important condition for a successful synthesis is good mixing - Nicodem
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byko3y
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[*] posted on 12-3-2017 at 11:34


I did not try exactly this one, but did something similar. Such additional entrainer as water leads to complex reactions of acetaldehyde with itself and ethylene glycol.
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Waffles SS
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[*] posted on 18-3-2017 at 09:32


US2042224 Process of converting a polyhydric alcohol to a carbonyl compound (Acetaldehyde from Ethylene glycol by Sulfuric acid at 150-175 C)

US2335238 By Zinc Chloride at -210-220 C

[Edited on 18-3-2017 by Waffles SS]
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clearly_not_atara
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[*] posted on 21-3-2017 at 13:50


Interesting. It seems that dilute sulfuric acid tends to favor the aldehyde where concentrated sulfuric acid may have given dioxane. However the requirement for pressurized reaction is an issue. Dilute sulfuric acid will lose water rapidly at 175 ÂșC. However it appears that you do get acetaldehyde by heating ethylene glycol in dilute sulfuric acid at 175 C under pressure while constantly replenishing water, although that may not be what byok3y envisioned when he said that.

The zinc chloride route is a vapor-phase reaction. That's kind of sad.

[Edited on 21-3-2017 by clearly_not_atara]
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