The present invention relates to a novel process for the preparation of compounds of the formula (I) ##STR00001## by reacting in a first step amino alcohols of the formula (II) ##STR00002## with oleum to give sulphuric acid esters of the general formula (III) ##STR00003## and by reacting these sulphuric acid esters in a second step with mercaptans or salts thereof of the general formula (IV) RSM (IV) wherein in each formula, where applicable, R.sup.1, R.sup.2, R.sup.3, R.sup.4, R.sup.5, R.sup.6, R, n and M have the meanings given in the disclosure, in the presence of a diluent and in the presence of a base.