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Topic: converting ester to acid carboxylic  (Read 4145 times)

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Offline mana

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converting ester to acid carboxylic
« on: August 26, 2017, 02:53:09 PM »
hi all
in the reaction below an acetophenone has reacted with dimethyl succinate.  my problem is how only on of the ester functional group convert to acid carboxylic not both of them (at the second process)???
is this reaction possible? :o

Offline mana

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Re: converting ester to acid carboxylic
« Reply #1 on: August 29, 2017, 03:46:27 AM »
hi all
in the reaction below an acetophenone has reacted with dimethyl succinate.  my problem is how only on of the ester functional group convert to acid carboxylic not both of them (at the second process)???
is this reaction possible? :o
I guess the question must have a mistake isn't it? because an ester can not convert to acid carboxylic with out water (hydrolysis)
I think I should add water at the first step of reaction

Offline sjb

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Re: converting ester to acid carboxylic
« Reply #2 on: August 29, 2017, 04:23:33 AM »
Look into variations of the Claisen condensation.

Offline mana

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Re: converting ester to acid carboxylic
« Reply #3 on: August 29, 2017, 04:32:53 AM »
Look into variations of the Claisen condensation.
you mean this?

Offline kriggy

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Re: converting ester to acid carboxylic
« Reply #4 on: August 29, 2017, 05:19:41 AM »
I suppose you could run the cyclization by just heating it with acid like H2SO4 or something. Then if if works, you can re-esterify the other COOH

Offline rolnor

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Re: converting ester to acid carboxylic
« Reply #5 on: August 29, 2017, 02:16:12 PM »
Is not the ketone alpha-protons more acidic than the esterprotons? In that case the first step would be very different.

Offline pgk

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Re: converting ester to acid carboxylic
« Reply #6 on: August 30, 2017, 10:44:47 AM »
Why don’t you try to draw the mechanism of the reaction?
Then, you can see how the one carboxylic group is formed, without hydrolysis.

Offline mana

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Re: converting ester to acid carboxylic
« Reply #7 on: September 03, 2017, 03:15:21 AM »
Is not the ketone alpha-protons more acidic than the esterprotons? In that case the first step would be very different.
the proton on malonate is btw two electron withdrawing group so I think the proton of malonate is more acidic than cetophenone

Offline mana

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Re: converting ester to acid carboxylic
« Reply #8 on: September 03, 2017, 03:18:41 AM »
Why don’t you try to draw the mechanism of the reaction?
Then, you can see how the one carboxylic group is formed, without hydrolysis.
I think in the first step as I have drawn in the last reaction first the proton of diester must be removed and the anion will attack the carbonyl group of ketone, the cyclization will form a lactone is it wrong? :-\

Offline rolnor

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Re: converting ester to acid carboxylic
« Reply #9 on: September 03, 2017, 06:45:49 AM »
But its not malonic ester, its succinic?

Offline mana

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Re: converting ester to acid carboxylic
« Reply #10 on: September 03, 2017, 04:28:16 PM »
But its not malonic ester, its succinic?
yes you are right I have written the name of di ester wrong, but what about the mechanism? is it wrong either?

Offline pgk

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Re: converting ester to acid carboxylic
« Reply #11 on: September 04, 2017, 09:26:26 AM »
Yes, it is right. This reaction is named “Stobbe Condensation”.
J. Am. Chem. Soc., 1950, 72(1), 514–517
DOI: 10.1021/ja01157a133
http://pubs.acs.org/doi/abs/10.1021/ja01157a133?journalCode=jacsat

Offline mana

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Re: converting ester to acid carboxylic
« Reply #12 on: September 07, 2017, 04:40:47 AM »
Yes, it is right. This reaction is named “Stobbe Condensation”.
J. Am. Chem. Soc., 1950, 72(1), 514–517
DOI: 10.1021/ja01157a133
http://pubs.acs.org/doi/abs/10.1021/ja01157a133?journalCode=jacsat
thanks :D

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