Process for the preparation of a 3-hydroxy-2,3-dihydrobenzisothiazole 1,1-dioxide and the use of this compound as a biocide and for preparing an ortho-sulphobenzimide.

摘要

The invention relates to a one-step process for the preparation of a 3-hydroxy-2,3-dihydrobenzisothiazole-1,1-dioxide in a high yield by oxidation of an ortho-toluene sulphonamide in the liquid phase using molecular oxygen and/or ozone in the presence of one or more catalysts. The oxidation is terminated before 50% of the starting material has been convented into resultant oxidation products from the 3-hydroxy-2,3-dihydrobenzisothiazole-1,1-dioxide and into other oxidation products. It is preferred that the reaction should be carried out in acetic acid or free of solvent using cobalt and/or manganese salts as a catalyst. The benzisothiazole-1,1-dioxides can be oxidized to an ortho-sulphobenzimide. In this way saccharin can be prepared. The bezsothiazole-1,1-dioxides also display biocidal activity.