O-aminobenzenesulfonic acid is a chemical substance with the molecular formula of c6h7no3s. Gray white acicular crystal. Gray white acicular crystal. Melting point > 300 ℃. It is soluble in concentrated hydrochloric acid, slightly soluble in water, insoluble in ethanol and ether. Reactive dye intermediates. Used for reactive brilliant red k-2b, brilliant red K-2BP, brilliant red k-2g, brilliant red m-2b, brilliant red X-B, brilliant red x-10b, reactive violet k-3r, etc.