Question

An alkyl bromide undergoes reaction in the alkaline medium to form the corresponding alcohol. When the concentration of the alkyl bromide is doubled keeping the concentration of the alkali constant, the rate of the reaction is doubled. When the concentration of the alkali is doubled keeping the concentration of the alkyl bromide constant, the rate of the reaction remains the same.

Write the mechanistic steps for the reaction and state the type of the reaction and the nature of the reagent.

Answer 1

The reaction is a nucleophilic substitution because a weaker nucleophile (Br⁻) is replaced by a stronger nucleophile (OH⁻). Since the rate of the reaction depends only on the concentration of alkyl bromide, it follows an SN₁ mechanism.

The reagent (OH⁻) acts as a nucleophile.

Mechanism:

Step 1: \[\ce{R - Br ->[ionisation] R+ + Br-}\]

Step 2: \[\ce{R + OH- -> ROH}\]

The reaction follows the process of racemisation and results in the formation of a racemic mixture.