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Topic: Benzaldehyde turned into solid?  (Read 8019 times)

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Offline third333

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Benzaldehyde turned into solid?
« on: April 28, 2010, 10:25:54 PM »
I am just curious if anyone knows why Benzaldehyde, if stored properly, would turn into a brown solid at the top of its container after a significant period of time? I guess for this to happen, storage must have been improper. Any ideas to why, or what the solid might be?

Could it have been exposed to air and water, and oxidized to Benzoic Acid?
« Last Edit: April 28, 2010, 10:36:09 PM by third333 »

Offline hobobot

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Re: Benzaldehyde turned into solid?
« Reply #1 on: April 28, 2010, 10:34:40 PM »
It's a very slow cannizzaro reaction. I think the solid is benzoic acid.

Offline Doc Oc

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Re: Benzaldehyde turned into solid?
« Reply #2 on: April 28, 2010, 11:51:44 PM »
Don't Cannizzaro's require hydroxide?  Otherwise I don't see how that can just disproportionate.

Offline orgopete

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Re: Benzaldehyde turned into solid?
« Reply #3 on: April 29, 2010, 12:56:36 AM »
Aldehydes are easily oxidized. It is benzoic acid.
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Offline nj_bartel

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Re: Benzaldehyde turned into solid?
« Reply #4 on: April 29, 2010, 04:01:39 AM »
^Agreed.

Distilled some benzaldehyde 2 years ago, blew a little nitrogen in, stoppered the flask, then parafilmed the stopper and stuck it in the fridge.  Still crystal clear liquid today - so just store it properly!

Offline pacifyer

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Re: Benzaldehyde turned into solid?
« Reply #5 on: May 12, 2010, 07:04:16 PM »
As said above, aldehydes oxidize easily, even by action of air, to give benzoic acid.

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