Metanilic Acid Synonyms: m-aminobenzenesulphonic acid, Aniline-m-sulphonic acid Empirical Formula: C6 H7 N S O3 CAS Number: 121 � 47 � 1 Purity ( Amine value) : 98 % Minimum Molecular Weight: 173.2 gm/ mol Appearance: White Powder Insolubles: 0.15 % Maximum Packing: 25 Kgs. / 50Kgs. HDPE woven bags with PE liner Applications: Intermediate for Optical Brightening Agents. Intermediate for Dyes. Intermediate for certain Sulpha Drugs.