Single correct · +4 / −1

The product of reaction of acetic anhydride with ethanol is:

  1. (a) Acetyl chloride
  2. (b) Ethyl acetate
  3. (c) Acetic acid
  4. (d) Diethyl ether
Answer and solution

Answer (b) Ethyl acetate

Solution

Chemistry ma’am · 3 steps

Ethanol attacks one acyl carbon of the anhydride, and the ester you get is the product to name.

  1. Spot the reaction. An acid anhydride reacts with an alcohol by nucleophilic acyl substitution. The oxygen of ethanol attacks one C=O carbon of acetic anhydride.
  2. What leaves. The acetate ion CH₃COO⁻ is the leaving group. It picks up the proton lost by ethanol and becomes acetic acid.

    (CH₃CO)₂O + C₂H₅OH → CH₃COOC₂H₅ + CH₃COOH

  3. So. The acetyl group joins the ethoxy group to give the ester ethyl acetate, CH₃COOC₂H₅. That is option (b).

The idea to keep. Any acid derivative plus an alcohol gives an ester. The acyl group moves to the alcohol's oxygen, and the leaving group of the derivative is set free.

Answer from the NTA final answer key. Solution by PrepWiser.

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