Reduction of a carboxylic acid with lithium aluminium hydride gives
Correct answer: B. a primary alcohol
- A. an aldehyde only
- B. a primary alcohol
- C. a ketone
- D. an alkane
Explanation
Lithium aluminium hydride is powerful enough to reduce the carboxyl group all the way to a primary alcohol, passing through the aldehyde without stopping there. Milder reducing agents such as sodium borohydride will not touch a carboxylic acid at all, which is why the choice of reagent matters. The reaction must be carried out in dry ether, since the reagent reacts violently with water.
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About Reactivity of Carboxylic Acids
Carboxylic acids show acidic behaviour because their carboxylate ions are resonance-stabilised, and electron-withdrawing groups can change their strength. Reactions include neutralisation, esterification, formation of acid chlorides and amides, reduction, decarboxylation and substitution at the acyl carbon, which differs from the reactions of phenols.
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550 free Carboxylic Acids MCQs from Chemistry, each with the correct answer and an explanation. Unlimited attempts, no account needed.
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