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VITEEE 2013 Paper

Section: Chemistry

Question : 69 of 120

Marks: +1, -0

In a Claisen condensation reaction (when an ester is treated with a strong base)

a proton is removed from the a -carbon to form a resonance stabilised carbanion of the ester
carbanion acts as a nucleophile in a nucleophilic acyl substitution reaction with another ester molecule
a new C—C bond is formed
All of the above statements are correct

Solution:

When two molecules of an ethylacetate undergo condensation reaction, in presence of sodium ethoxide involving the reaction is called as Claisen condensation and product is a β - keto ester

2\mathrm{CH}_3\mathrm{CH}_2\overset{\mathrm{O}}{\overset{\parallel}{\mathrm{C}}}\mathrm{OCH}_3

\xrightarrow[\text{(ii) }\mathrm{H}^{+}]{\text{(i) }\mathrm{CH}_3\mathrm{O}}

\mathrm{CH}_3\mathrm{CH}_2\underset{\beta}{\overset{\mathrm{O}}{\overset{\parallel}{\mathrm{C}}}}\underset{\mathrm{CH}_3}{\underset{\vert_{\alpha}}{\mathrm{C}}}

\overset{\mathrm{O}}{\overset{\parallel}{\mathrm{C}}}\mathrm{OCH}_3

\mathrm{CH}_3\mathrm{OH}

Mechanism

Step I

Step II

Step III

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