This invention relates to a process for replacing one or more chlorine atoms on an aromatic ring with sulfonyl groups. In particular, it relates to the reaction of a ring chlorinated aromatic aldehyde or carboxylic acid with a sulfite or a bisulfite in water at a high pH.
The sodium salt of ortho-sulfonylbenzaldehyde (OSBAL) is an important chemical intermediate in the food, dye, and electroplating industries. In DE88952, it is prepared by reacting orthochlorobenzaldehyde (OCBAL) with sodium bisulfite in a neutral medium in an autoclave at 190 to 200.degree. C. and 8 atmospheres pressure (810 kPa) for 8 hours. In DE 2502912, it is prepared by reacting OCBAL with sodium sulfite in an autoclave in the presence of a KI catalyst at 140 to 150.degree. C. and 7 atmospheres pressure (709 kPa) for 3 hours. However, these processes do not produce OSBAL at the desired yield and purity levels.