MDCAT Chemistry MCQ #394

The mechanism of nucleophilic addition to a carbonyl group changes depending on the catalyst. What is the first step in acid-catalyzed addition?

MDCAT Chemistry MCQ #394

  1. Question 1

    Q1. The mechanism of nucleophilic addition to a carbonyl group changes depending on the catalyst. What is the first step in acid-catalyzed addition?

    • A) Attack of the nucleophile on the carbonyl carbon
    • B) Formation of a carbanion intermediate
    • C) Deprotonation of the alpha-carbon
    • D) Protonation of the carbonyl oxygen atom

    Answer: Protonation of the carbonyl oxygen atom

    Explanation: In acid-catalyzed addition, protonation of the carbonyl oxygen occurs first. Option A is the first step in base-catalyzed mechanisms.