Common Name: Benzenesulfonic acid English Name: Benzenesulfonic acid CAS Number: 98-11-3 EINECS: 202-638-7 Molecular Formula: C6H6O3S Molecular Weight: 158.175 Density: 1.4±0.1 g/cm3 Boiling Point: 137°C Melting Point: 30-60°C Flash Point: >230°F Appearance: Colorless needle-like or flaky crystals. Solubility: Highly soluble in water and ethanol, slightly soluble in benzene. Uses: 1. Used as a laboratory reagent, catalyst, and in organic synthesis and phenol production. 2. Primarily used in the production of phenol via alkali fusion, as well as in the synthesis of resorcinol. Commonly employed as a catalyst in esterification and dehydration reactions. 3. Benzenesulfonic acid is used in oilfield water injection to alleviate formation blockages and enhance permeability. As an acid for acidizing injection wells, it reacts slowly with carbonates, with slower reaction rates at higher concentrations, enabling deep formation acidization. Compared to hydrochloric acid, benzenesulfonic acid (and mixed aryl sulfonic acids) offers longer effectiveness, lower corrosiveness, and safer usage. It also serves as a catalyst in esterification and dehydration reactions and as a curing agent in the foundry industry. 4. Used in the detection of ammonium and potassium salts, determination of zinc, organic synthesis, production of phenol and resorcinol, and as a catalyst. Functions as a dehydration catalyst, resin curing agent, electroplating additive, and dye intermediate. Primarily used in phenol production via alkali fusion and as a catalyst in esterification and dehydration reactions.