Destroyer Orgo # 9

[topdent1]

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Why will the COOH group with the beta keto acid decarboxylate?

 

[Orgodox]

Thats what happens check out the link to see the mech-- beta keto acids decaroxylate.

http://www.cem.msu.edu/~reusch/VirtualText/Images2/crbacrx6.gif

after loss of CO2 its simple keto-enol tautomerization

 

[TeamGuo]

if you do the decarbox mech. you will see why you need a carbonyl on the beta position.

In this case that beta carbonyl oxygen will grab the H and start off the decarbox mechanism.

So you will be releasing CO2 from the carbox group.

This is why under high heat, if you have carbox. acid and a carbonyl or 2 carboxylic acid sharing an alpha carbon is unstable. One of the carbox. acid will decarboxylate.

 

[topdent1]

One other thing, anyone know the mechanism or 'why' the alpha hydrogens are removed and replaced by deuteriums in number 31 of destroyer? Its probably something simple...

 

[TeamGuo]

One other thing, anyone know the mechanism or 'why' the alpha hydrogens are removed and replaced by deuteriums in number 31 of destroyer? Its probably something simple...

Yea, you have a methyl ketone as the starting material. You have acidic alpha protons, so the D2O will deprotonate it to make an enolate and then grab the D off of DCl. This is analagous to the Iodoform reaction. So you repeat this mech. 3 times to get 3 D's on the alpha carbon.

It's one of those not so useful destroyer questions. kk