We are one of India's leading manufacturers, exporters & suppliers of 4 B Acid. Its chemical name is 2-Amino-5-methylbenzenesulfonic acid. The CAS Number of 4 B Acid is 88-44-8 and its chemical formula is C7H9NO3S. The most common end use is Pigments and its various other synonyms are 4-Aminotoluene-3-sulfonic acid; Ptmsptmsa; PTMS; PTMSA .