Question

For the Acetylation of Aniline distilled aniline is added to a round bottom flask along with acetic anhydride, glacial acetic acid and Zinc dust. The zinc acts as a catalyst for the reaction.

Explain how the Zn added to the reaction catalyses the reaction. hint: what happens at first when Zn reacts with strong acid

Answer 1

Acetylation of Aniline Reaction:

The Zinc dust uses to prevent the oxidation of aniline. If oxidation happens acetylation reaction will disturb. Zinc surface act as an absorbent so which will remove the colour impurities.

Zn dust reacts with glacial acetic acid gives the zinc acetate and hydrogen gas. This reaction prevents oxidation of aniline by acetic acid.

  Zn + CH3COOH    Zn(CH3COO)2 + H2