Benzenesulfonyl chloride, DMSO

In absence of diluent or other effective control of reaction rate, the sulfoxide reacts violently or explosively with the following acetyl chloride, benzenesulfonyl chloride, cyanuric chloride, phosphorus trichloride, phosphoryl chloride, tetrachlorosilane, sulfur dichloride, disulfur dichloride, sulfuryl chloride or thionyl chloride [1]. These violent reactions are explained in terms of exothermic polymerisation of formaldehyde produced under a variety of conditions by interaction of the sulfoxide with reactive halides, acidic or basic reagents [2]. Oxalyl chloride reacts explosively with DMSO at ambient temperature, but controllably in dichloromethane at —60°C [3]. See Carbonyl diisothiocyanate, and Dinitrogen tetraoxide, and Hexachlorocyclo-triphosphazine, and Sodium hydride, all below See Perchloric acid Sulfoxides... 

Imidazole (6.8 g, 0.1 mol) is dissolved in DMSO (50 ml), and 1 cq. of powdered potassium hydroxide is added. When this has dissolved, the solution is cooled to 0°C, and benzenesulfonyl chloride (17.7 g, 0.1 mol) is added during 30min. The reaction mixture is then poured into water (l(X)ml) and extracted with chloroform (3 x 50ml). The organic extracts are washed with water, dried and evaporated to give a yellow oil, which usually solidifies on evacuation (12.4 g, 60%). Recrystallization from chloroform-hexane gives the pure product (8.2 g, 40%), m.p. 78°C. 

The target triazolo[l,5-c]pyrimidine sulfonamides 6 were prepared via coupling 7 with substituted benzenesulfonyl chlorides (Scheme 2). In these transformations, pyridine and a catalytic amount of dimethylsulfoxide (DMSO) were essential for the formation of 6. The reactive intermediate is believed to be the in situ generated sulhlimine 10 which allows for the relatively non-nucleophiKc amines to react with sulfonyl chlorides under mild conditions [7-8],... 

The rates of aminolysis of benzenesulfonyl chloride by a series of m- and p-substituted benzylamines in mixtures of MeCN and DMSO increased up to 0.5 mol fraction of DMSO, but thereafter remained nearly constant. Analyses of the rate data using Kamlet—Taft s solvatochromic parameters revealed that solvent H-bonding and polarizability were important in the solvation of the trigonal bipyramidal transition state that was formed during a proposed Sivf2(S) process. ... 

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