Question

Propose a mechanism for proton exchange of an alcohol in aqueous base.

Short answer

Mechanism for proton exchange of an alcohol in aqueous base is shown below.

Step-by-step solution

Step-by-Step SolutionStep 1: Proton exchange

When alcohol reacts with a base, proton exchange is faster. These results in spectrum appear to be only one singlet peak for proton. Due to fast proton exchange reaction, adjacent protons don’t split. Thus, proton exchange reaction doesn’t cause splitting.

Explanation of the mechanism

Mechanism

When alcohol and base react together, protons bonded to oxygen undergo proton exchange with base. In the mechanism, NaOH base deprotonates methanol and gives alkoxide ion. Methanol undergoes bond cleavage in O-H bond and then proton gets transferred to the base, which results in methoxide and water as products.