3d-orbital resonance in divalent sulphide—XIII : The E2 reaction of p-substituted β-phenylmercapto chlorides and the corresponding oxygen analogues

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The rates of the base-catalysed elimination of a series of p-substituted-β-phenylmercaptoethyl chlorides and the corresponding oxygen analogues have been determined both in t-butanol containing potassium t-butoxide and in ethanol containing sodium ethoxide. The rates of the E2 reaction of the sulphur compounds are found to be 10 2–10 3 times as great as those of the corresponding oxygen analogues in both media. These rates can be correlated with Hammett σ values. The ρ values obtained for sulphur compounds are 1·98 and 2·14 in t-butanol and ethanol, while those for oxygen analogues are 1·33 and 1·50 respectively. The faster kinetics rates and the higher Hammett ρ values of the sulphur compounds, as compared with the oxygen counterparts suggest the 3d-orbital resonance is important in the E2 elimination reactions of these sulphur compounds. Other implications of the rates and the effect of the substituent are discussed.