REACTIONS OF CUMYLIC CHLORIDES WITH SODIUM THIOPHENOXIDE

Treatment of p-nitrobenzyl chloride, bromide, and iodide (and also m-nitrobenzyl chloride, bromide, and iodide) with sodium thiophenoxide in DMF results in a clean reaction yielding the corresponding benzyl sulfides. The reactions are all extremely rapid, half-lives in all instances being less than one minute at 0(DEGREES) and 0.1 M. Since these studies were undertaken to investigate a possible leaving group effect of the benzyl halides it was clear that useful kinetic data could not be obtained without the use of special techniques. Consequently, compounds containing more difficultly displaced leaving groups were studied. Specifically, the reactions of p-nitrobenzyl phenyl ether and p-nitrobenzyl phenyl sulfide with sodium thiophenoxide were investigated. These reactions prove not to be clean; but, interestingly, they give significant amounts of p-nitrobenzyl diphenyl mercaptal. Treatment of p-nitrocumyl chloride with sodium thiophenoxide in DMF for 2.5 hours leads to a 95% yield of the tertiary substitution product, p-nitrocumyl phenyl sulfide. The half-life of the reaction is two minutes. This behavior is in contrast to that of cumyl chloride, which not only requires six days for complete reaction, but also gives only a 4% yield of the tertiary substitution product, cumyl phenyl sulfide; a-methyl styrene is the only other product. The half-life of this reaction is 25 hours, a factor of 700 times slower than the reaction of p-nitrocumyl chloride. It is proposed that substitution at the tertiary carbon center of p-nitrocumyl chloride proceeds via a radical anion chain mechanism. . . . (Author\u27s abstract exceeds stipulated maximum length. Discontinued here with permission of school.) UM