Reaction of N-alkyl-2-benzothiazolesulphenamide with acetic anhydride in the presence of acids I. Technological aspects

The reaction of N-alkyl-2-benzothiazolesulphenamide with acetic anhydride i n a non-polar solvent and in the presence of carboxylic or mineral acids at temperatures of 50-90 degreesC has been studied. At low initial concentrat ion of an acid or in its absence a typical autocatalytic behavior of the re action is observed. However, at higher concentration of acetic acid (>3 mol dm(-3)), phosphoric or sulphuric acid (>0.2 mol dm(-3)) the autocatalytic course of the reaction disappeared and higher rate of an N-alkyl-2-benzothi azolesulphenamide conversion was observed. The molar ratio of formation of the desired product, alkylbis(2-benzothiazolylsulphen)amide, to the main by -product, alkylamide of acetic acid, is up to 1.6 in the acid catalyzed rea ction. The type of alkyl derivatives of 2-benzothiazolesulphenamide has a s trong effect on the rate of formation of the corresponding alkylbis (2-benz othiazolylsulphen) amide. The yield of alkylbis(2-benzothiazolylsulphen) am ides varies between 80-20 mol% at total conversion of the corresponding sul phenamides in the following order: IPbisBS > CHbisBS > TBbisBS > TAbisBS. ( C) 2001 Elsevier Science B.V. All rights reserved.