Mechanism of the reaction of N-p-tosylsulphilimine and related compounds with thiophenolate ion |
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Authors: | Shigeru Oae Tetsuo Aida Masashi Nakajima Naomichi Furukawa |
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Institution: | Department of Applied Chemistry, Faculty of Engineering, Osaka City University, Sugimoto-cho, Sumiyoshi-ku, Osaka, Japan |
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Abstract: | The reaction of alkyl aryl N-p-tosylsulphilimines with thiophenolate ion was found to afford quantitatively the sulphide that arises by an SN2 like reaction on the carbon atom adjacent to the tri-valent sulphur atom. This reaction was also found to proceed smoothly with such compounds as sulphoxides and sulphones and sulphoxmanes. The kinetic study on the reaction between aryl methyl N-p-tosylsulphilimine with thiophenolate ion in DMF reveals that the reaction is of second order, namely, first order with respect to each thiophenolate ion and the sulphilimine. The enthalpy and entropy of activation for the reaction are ΔH≠ = ?17· kcal/mol and ΔS≠ = ?5·7 eu respectively. The effect of substituents in the reaction, p-XC6H4+(?SO2C6H4Y-p)CH3 + p-ZC6H4SK is nicely correl with Hammett σ values giving ?x = + 2·4, ?y = + 1·2 and ?z = ?1·8 respectively. Meanwhile, a marked steric retardation by a bulky alkyl group in alkyl phenyl N-p-tosylsulphilimine is observed. Furthermore, from the stereochemical study of the reaction using an optically active sec-octyl phenyl N-p-tosylsulphilimine with thiophenolate ion it is concluded that the reaction proceeds via a typical SN2 process on α-carbon atom attached to the tri-valent sulphur atom. |
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