The Birch reduction of benzoic acid gives:

The Birch reduction is a chemical reaction commonly used to reduce aromatic compounds, such as benzene rings, using alkali metals like sodium or lithium in the presence of liquid ammonia (NH3) or an ammonia-based solvent. This reduction typically results in the formation of cyclohexadienes.

In the case of benzoic acid, which has a benzene ring attached to a carboxylic acid functional group, the Birch reduction can lead to the formation of cyclohexadienes with specific substitution patterns. The exact product obtained depends on reaction conditions, including the choice of metal and the presence of other reactants.