Synthesis of benzocaine

Benzocaine, ethyl 4-aminobenzoate, is a local anaesthetic used in gels and throat lozenges. It is prepared in two steps from 4-nitrobenzoic acid, obtained by oxidation of 4-nitrotoluene.

Fischer esterification with ethanol and sulfuric acid gives ethyl 4-nitrobenzoate. Catalytic hydrogenation over palladium on carbon reduces the nitro group to amino without affecting the ester or the ring; it can also be done with iron or tin in acid. If the nitro group is reduced first, the resulting amino acid is harder to esterify, because the amino group is protonated.