Benzenesulfinic acid is primarily used in organic synthesis as a reducing agent and intermediate. It plays a key role in the preparation of sulfones and sulfoxides through oxidation reactions. Additionally, it is utilized in the synthesis of pharmaceuticals, agrochemicals, and dyes. Its ability to act as a nucleophile makes it valuable in creating carbon-sulfur bonds in complex organic molecules. In polymer chemistry, it is employed as a chain transfer agent to control molecular weight during polymerization processes. It also finds application in the production of specialty chemicals and as a reagent in various catalytic reactions.