Sulphenyl halides, reaction + acetylenes

Addition reactions of sulphenyl halides (in particular chlorides) to acetylene derivatives have been extensively explored and recently reviewed (Modena and Scorrano, 1968). Although free radical processes may be involved under specific conditions, the addition of both arene-and alkanesulphenyl halides normally occurs by an ionic mechanism, the sulphenyl halide sulphur being the electrophilic centre. 

The reactions of acetylenes with sulphenyl halides and related compounds have been reviewed. A-(Benzenesulphenyl)-/ -nitroaniline (326) reacts with 1 -pentyne in acetonitrile in the presence of boron trifluoride etherate to yield solely the 2-azabutadiene derivative 327235. 

The order of susceptibility towards substituent effects is much less in the acetylene series than in the olefins, but its direction is similar. A similar statement may be made about the direction, rates, and kinetics of addition of sulphenyl halides. While the simple acetylenes, such as sym-diphenylacetylene and 3-hexyne, required catalytic quantities of aluminium chloride before undergoing addition by 2,4-dinitrobenzene sulphenyl chloride , the rates of reaction of acetylene itself with some p-substituted benzene sulphenyl chlorides alone have been measured. The effect of the p-substituents... 

Sulphenyl Halides.— Illustrative procedures for the synthesis of sulphenyl halides reported during the period under review employ well-established methods, Tetrachloropyridine-4-sulphenyl chloride is obtained from the corresponding disulphide by chlorinolysis, while the corresponding sulphonyl chloride is formed in AcOH or hydroxylic media. 2-Methyl-2-propanesulphenyl iodide is obtained from the thiol with la, or from the sulphenamide with HI addition reactions of selenium dichloride, or seleninyl chloride, to acetylene are specific examples of generally applicable reactions - (HC=CH + SeCU C1CH=CH-Se-Cl). The chlorination of CSa under activated charcoal catalysis has been developed as a continuous process, giving trichloromethanesulphenyl chloride. 

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See also in sourсe #XX -- [ , ]

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