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Aldehydes, Ketones and Carboxylic Acids

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In the following reaction sequence, the compound J is an intermediate.

\xrightarrow[\mathrm{CH_3COONa}]{\mathrm{(CH_3CO)_2O}}

\xrightarrow[\text{(ii) }\mathrm{SOCl}_2,\text{(iii) anhyd. }\mathrm{AlCl}_3]{\text{(i) }\mathrm{H}_2,\mathrm{Pd}/\mathrm{C}}

J(\mathrm{C_9H_8O_2})

gives effervescence on treatment with

\mathrm{NaHCO}_3

anda positive Baeyer’s test.

Section: Chemistry

Question : 55 of 77

Marks: +1, -0

The compound I is

[JEE Adv 2012 P2]

Validate

Solution:

In the given reaction, an aromatic aldehyde is condensed with an acid anhydride (Perkin condensation) in the presence of a base to form α,β-unsaturated acid (cinnamic acid). This gives effervescence on reaction with

\mathrm{NaHCO}_3

and positive test with Bayer’s reagent (1 % alkaline

\mathrm{KMnO}_4

\underset{I}{\mathrm{Ph-CHO}}

\xrightarrow[\mathrm{CH_3COONa}]{}\mathrm{(CH_3CO)_2O}

\underset{\text{J (Cinnamic acid)}}{\mathrm{Ph-CH= -\,COOH}}

\xrightarrow{\mathrm{NaHCO}_3}

Effervescence

Cinnamic acid

\xrightarrow[\text{(Bayer's reagent)}]{\text{1\% cold, alk};\,\mathrm{KMnO}_4}

Positive

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