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Chemistry Forums for Students => Organic Chemistry Forum => Topic started by: jammie on August 27, 2015, 09:56:36 AM

Title: Organic chemistry mechanism problem
Post by: jammie on August 27, 2015, 09:56:36 AM

I'm really stuck on deciphering the mechanism for the attached reaction. I've draw out the hydrogen bonding and have been trying to eliminate CO2 but keep ending up with the carbonyl in the wrong place. I'm not really seeing any driving forces. Help needed please!

Title: Re: Organic chemistry mechanism problem
Post by: Shadow on August 27, 2015, 11:33:36 AM

1) Write the side products of the reaction;
2) If decarboxylation doesn't work as the first step, what other reaction could happen first, to produce one of the side products?

Title: Re: Organic chemistry mechanism problem
Post by: jammie on August 27, 2015, 01:27:50 PM

Quote from: Shadow on August 27, 2015, 11:33:36 AM

1) Write the side products of the reaction;
2) If decarboxylation doesn't work as the first step, what other reaction could happen first, to produce one of the side products?

So the side products are carbon dioxide and water... Ah ok I think I got it: elimination of water followed by tautomerism and then decarboxylation. Makes sense, thank you :)

Title: Re: Organic chemistry mechanism problem
Post by: Shadow on August 27, 2015, 05:02:17 PM

Exactly. The γ-ketoacid decarboxylates readily. Whether the elimination happens as an E2 or E1 process is questionable.