We are leading manufacturer in Metanilic Acid. It is also known as Meta Amino Benzene Sulphonic Acid, chemical formula is C6H 5 S0 3 H,11H 2 O, crystallizes in small plates and is very deliquescent. Benzene sulphochloride, C6H5 S02C1, is a colourless fuming liquid which boils at 120° C. (10 mm.).
The aminobenzene sulphonic acids, particularly the meta and para compounds, are of importance owing to their employment in the colour industry. The direct sulphonation of aniline yields the para acid, sulphanilic acid, C 6 H 4 (NH 2)(SO 3 H), which crystallizes in small plates and is sparingly soluble in cold water. When fused with caustic potash it yields aniline, whilst oxidation with chromic acid yields benzoquinone. In constitution it is probably to be regarded NH3 as a cyclic ammonium salt, C 6 H 4 When diazotized in NS0 3 .
Acid solution and coupled with dimethyl aniline it yields helianthine, the sodium salt of which is used as an indicator. Metanilic acid C6H4(NH2) (S03H) [1.3], which crystallizes in prisms, is formed b y the reduction of meta-nitrobenzene sulphonic acid and is used in the preparation of various azo dyes.