Reactions of organo sulfur compounds with superoxide ion

Abstract

The reactions of 2,4-dinitrobenzenesulfonyl chloride, and o-nitrobenzenesulfonyl chloride with potassium superoxide ($KO_2$) were carried out at -35$^\circ$C -0$^\circ$C in various solvents such as dimethyl sulfoxide, tetrahydrofuran, and acetonitrile in order to study on the peroxy-intermediates such as peroxy-sulfenate and sulfonate which have been postulate to be unstable intermediate. The treatment of two arylsulfonyl chlorides with $KO_2$ gave only one product, i.e., the corresponding potassium sulfonate in good yields. The reactions appear to be initiated by a nucleophilic attack of superoxide ion ($O_2^{\bar{\cdot}}$) on the sulfur atom to form peroxy-sulfonate intermediates, which convert to the corresponding sulfonates. When dimethyl sulfoxide was used as a trapping agent for the peroxy oxygen of peroxy-sulfonate intermediate, actually dimethyl sulfone of oxidation product along with the sulfonate was obtained in good yield. Thus, the reaction of arylsulfonyl chloride with $O_2^{\bar{\cdot}}$ undoubtedly is initiated by forming peroxy-sulfonates, which are available as a new oxidizing reagent under mild condition in aprotic organic solvents. While, the reactions of 2,4-dinitrobenzenesulfenyl chloride, and o-nitrobenzenesulfenyl chloride with $KO_2$ in THF or $CH_3CN$ gave the corresponding sulfonates and interestingly the corresponding disulfide were also obtained. In the case of 2,4-dinitrobenzenesulfenyl chloride, only bis (2,4-dinitrophenyl) disylfide was obtained as main product. From the observation of these facts the reactions appear to be initiated by a nucleophilic attack of $O_2^{\bar{\cdot}}$ on the sulfenyl sulfur atom to form a peroxy-sulfenate intermediate, which may compete two pathways: one is proceeded via cleavage of peroxy-sulfenate intermediate to form thiyl radical yielding the disulfide, and the other is converted to peroxy-sulfenate intermediate yielding the sulfonate. The reactions of 1,3-disubstituted thioureas with $O_2^{\bar{\...