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MolSynapse / Question bank / Aldehydes, Ketones and Carboxylic Acids / Oxidation and reduction of carbonyls (Clemmensen, Wolff-Kishner, Tollens, Fehling)

JEE Advanced levelSingle correct optionDifficulty 3 of 3co153

5-Hydroxy-5-methylhexan-2-one, $CH X_{3} COCH X_{2} CH X_{2} C (CH X_{3}) X_{2} OH$ , is to be reduced so that the ketone carbonyl becomes $CH X_{2}$ . Which reagent choice and product are correct?

AClemmensen reduction; 2-methylhexan-2-ol
BClemmensen reduction; 2-chloro-2-methylhexane
CWolff-Kishner reduction; 5-methylhexan-2-ol
DWolff-Kishner reduction; 2-methylhexan-2-ol

Answer: D

The tertiary alcohol is acid-sensitive: in conc.

HCl

it would be replaced by chloride or dehydrate, so Clemmensen is unsuitable. Under the basic Wolff-Kishner conditions the alcohol is stable and

C = O

becomes

CH X_{2}

, giving

CH X_{3} CH X_{2} CH X_{2} CH X_{2} C (CH X_{3}) X_{2} OH

, 2-methylhexan-2-ol.

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