m-hydroxybenzenesulphonic acid

ChEBI: An arenesulfonic acid that is phenol substituted by a sulfo group at C-3.

M-hydroxybenzenesulphonic acid is synthesized by the reaction of 1,3-benzenedisulfonic acid and sodium hydroxide in water in an autoclave for 30 h at 250 ℃. The reaction mass is neutralized and evaporated to dryness. The sodium salt of the acid is extracted with 78% ethyl alcohol; yield 78%]. The crude solution obtained by acidifying the reaction mass with hydrochloric acid and freeing it from sulfur dioxide by boiling can be used in the manufacture of dyes.