Patent ID: 6891060

Claim:
Process for preparing compounds of the formula (I) where R 1 is C 1 -C 20 -alkyl, C 7 -C 20 -arylalkyl, C 13 -C 20 -diarylalkyl or radicals of the formulae (IIa) or (IIb) A—OR 2 (IIa) A—NR 3 R 4 (IIb) where A is in each case a C 1 -C 4 -alkylene radical and R 2 and also R 3 and R 4 are each independently methyl, ethyl and isopropyl, comprising reacting a) compounds of the formula (III) where M is in each case independently hydrogen, ammonium, an alkali metal or half of an equivalent of an alkaline earth metal, with alkali metal hydroxide in the presence of water and b) partially neutralizing the reaction mixtures obtained in step a) and c) reacting the reaction mixtures obtained in step b) with compounds of the formulae (IVa) or (IVb) R 1 —COX (IVa) (R 1 —CO) 2 O (IVb) where the R 1 radicals are in each case independently as defined above and d) acidifying the reaction mixtures obtained in step c).