Patent ID: 6936732

Claim:
A process for the preparation of sulphonated phenols of the general formula I where R 1 is hydrogen, a C 1 -C 20 alkyl group which is unsubstituted or substituted by halogen, cyano, hydroxyl, C 1 -C 20 alkoxy, C 2 -C 20 alkoxycarbonyl, acyloxy and/or phenyl which is unsubstituted or substituted by C 1 -C 4 alkyl, C 1 -C 4 alkoxy and/or halogen, R 2 is hydrogen, C 1 -C 20 alkyl or benzoyl of the general formula II where R 3 and R 4 independently of one another are each hydrogen, halogen, C 1 -C 12 alkyl, C 1 -C 12 alkoxy, C 1 -C 4 haloalkyl, C 3 -C 8 cycloalkyl, C 4 -C 12 cycloalkylalkyl, cyano, hydroxyl, or hydroxyethyl or are each phenoxy, C 7 -C 10 phenylalkyl or phenyl which is unsubstituted or substituted by C 1 -C 4 alkyl, C 1 -C 4 alkoxy and/or halogen, and R 5 is hydrogen or the group SO 3 X where X can be hydrogen, a monovalent metal or a group —N(R 6 ) 3 , where each of the three radicals R 6 can be independently of one another hydrogen, C 1 -C 6 alkyl or C 1 -C 6 hydroxy alkyl which process comprises reacting a phenol of the general formula III where R 1 and R 2 are as defined above, with a halosulphonic acid in a solvent which is a mixture of a C 5 -C 10 aliphatic or cycloaliphatic hydrocarbon and a dialkyl carbonate of the general formula IV R 7 —O—CO—O—R 8 IV where R 7 and R 8 each represent independently a C 1 -C 4 alkyl group.