Applications
Benzenesulfonic acid is mainly consumed by conversion to other specialty chemicals. A variety of pharmaceutical drugs are prepared as salts of benzenesulfonic acid and are known as besylates or besilates. The alkali metal salt of benzenesulfonic acid was once widely used in the production of phenol. It acts as an acid catalyst for direct esterification of amino acids and peptides.

Solubility
Soluble in water and alcohol. Slightly soluble in benzene. Insoluble in non-polar solvents.

Notes
It is hygroscopic. Incompatible with oxidizing agents and bases.