p-Hydroxybenzenesulfonic acid

P-Hydroxybenzenesulfonic acid (CAS 98-67-9), also known as p-Sulfophenol, 4-Sulfophenol, and Sulfocarbolic Acid, is an aromatic sulfonic acid carrying both a hydroxyl and a sulfonate group on a benzene ring. It carries no assigned E-code and is classified under HS code 29089990.

In textile and leather processing, it acts as a dye-bath auxiliary, where the sulfonate group improves dye solubility and fiber affinity. In personal care formulations, it functions as an antimicrobial and UV-absorbing agent, disrupting microbial cell membranes while absorbing UV radiation through its conjugated aromatic system.

The material is supplied as a yellowish oily liquid, typically in industrial drum and IBC formats. It falls under REACH registration requirements for EU supply and should be accompanied by a compliant Safety Data Sheet. No Ph.Eur. or FCC monograph applies; buyers should request certificate of analysis for purity specification confirmation.