MDCAT Chemistry MCQ #345

In the reaction of aldehydes with 2,4-DNPH, the pH must be carefully controlled. Why does the reaction fail in extremely acidic conditions?

MDCAT Chemistry MCQ #345

  1. Question 1

    Q1. In the reaction of aldehydes with 2,4-DNPH, the pH must be carefully controlled. Why does the reaction fail in extremely acidic conditions?

    • A) The carbonyl oxygen becomes too stable
    • B) The product undergoes immediate hydrolysis
    • C) The amino group is protonated and loses nucleophilicity
    • D) The buffer solution reacts with the aldehyde

    Answer: The amino group is protonated and loses nucleophilicity

    Explanation: A pH of 3-4 is required for ammonia derivatives. Highly acidic conditions (pH 1) protonate the nitrogen, making it non-nucleophilic and inactive.