The present invention relates to a process for the preparation of compounds of the formula (1)R.sup.1 R.sup.2 R.sup.3 R.sup.4 R.sup.5 ArCOOR (1)in which R.sup.1, R.sup.2, R.sup.3, R.sup.4 and R.sup.5 are identical or different and are hydrogen, a halogen, an alkyl or alkoxy group having 1 to 6 carbon atoms or OR, NHR, NR.sub.2, SR or COOR, in which R is an alkyl radical having 1 to 4 carbon atoms, Ar is an aryl radical having 6 to 12 carbon atoms and the radical R shown in formula (1) has the above meaning, by reacting a compound of the formula (2)R.sup.1 R.sup.2 R.sup.3 R.sup.4 R.sup.5 ArCOOH (2)in which R.sup.1, R.sup.2, R.sup.3, R.sup.4 and R.sup.5 are identical or different and are hydrogen, a halogen, an alkyl or alkoxy group having 1 to 6 carbon atoms, OH, NH.sub.2, NHR, SH or COOH and Ar has the same meaning as in formula (1), with a sulfate of the formula (RO).sub.2 SO.sub.2, in which R has the above meaning, in the presence of a water-insoluble tertiary amine and water at a temperature of 10.degree. to 120.degree. C. in the presence or absence of a water-insoluble solvent and with the addition of a base, at a pH of 5 to 12.