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How does benzyl bromide react with sodium hydroxide to form benzyl alcohol?

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dissociation of E–N — reaction mechanism Possible energy diagram for the dissociation of a covalent molecule, E–N, into its ions E⁺ and N⁻ (see text).

The conversion of benzyl bromide to benzyl alcohol using sodium hydroxide is a classic example of a substitution reaction.12

In this process, the hydroxyl group from the sodium hydroxide acts as a nucleophile, replacing the bromine atom on the benzyl bromide molecule. The displaced bromine atom then combines with the sodium ion to form sodium bromide as an inorganic by-product.12

Regarding the reaction mechanism, such substitutions on alkyl halides typically occur via an $S_{N} 2$ (substitution-nucleophilic-bimolecular) pathway. In this one-step process, the nucleophile approaches the carbon atom from the side opposite the leaving group (the bromine atom), forming a transition state where the carbon is partially bonded to both the incoming hydroxyl group and the outgoing bromine. The rate of this reaction is influenced by the structure of the alkyl halide, specifically the degree of steric hindrance at the reactive carbon site.3