Solved: CHEMISTRY Question for NEET

NEET CHEMISTRYMedium

Mark the reaction among the following that does not give benzoic acid as the major product:

$C_6H_5COCH_3 \xrightarrow{\text{(i) } NaOBr \text{ (ii) } H^+}$

$C_6H_5CH_3 \xrightarrow{KMnO_4/KOH, \Delta}$

$C_6H_5CN \xrightarrow{H_3O^+}$

$C_6H_5CH_2OH \xrightarrow{\text{PCC}}$

The question tests the knowledge of oxidation reactions yielding carboxylic acids versus aldehydes.

Haloform Reaction: Acetophenone ( $C_6H_5COCH_3$ ) contains a methyl ketone group. Treatment with $NaOBr$ (sodium hypobromite) followed by acidification oxidises it to Benzoic acid ( $C_6H_5COOH$ ).
Side-Chain Oxidation: Alkylbenzenes like Toluene ( $C_6H_5CH_3$ ) having at least one benzylic hydrogen are oxidised by strong oxidising agents like alkaline $KMnO_4$ to Benzoic acid.
Hydrolysis of Nitriles: Benzonitrile ( $C_6H_5CN$ ) upon complete acid hydrolysis ( $H_3O^+$ ) yields Benzoic acid.
Mild Oxidation: PCC (Pyridinium Chlorochromate) is a mild oxidising agent used to convert primary alcohols to aldehydes. It prevents further oxidation to carboxylic acids. Therefore, the reaction of Benzyl alcohol ( $C_6H_5CH_2OH$ ) with PCC yields Benzaldehyde ( $C_6H_5CHO$ ), not benzoic acid.

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