REACTIVITY OF NUCLEOPHILES TOWARD AND THE SITE OF NUCLEOPHILIC-ATTACK ON PHENYL BENZENETHIOLSULFINATE

The reactivity of 12 common nucleophiles toward phenyl benzenethiolsulfinate, PhS(O)SPh (1), has been measured and compared with their reactivity toward phenyl benzenethiolsulfonate, PhSO2SPh, under the same conditions. Whether nucleophilic attack on 1 occurs preferentially on the sulfinyl (>S͇O) or on the sulfenyl (>S) sulfur has been determined for those nucleophiles where the nature and stability of the substitution products make this possible. The principal conclusions are as follows. (1) Except for oxyanions, such as CH3O- and OH-, most nucleophiles prefer to attack the sulfenyl rather than the sulfinyl sulfur. (2) Besides being the one type of nucleophile that prefers to attack the sulfinyl sulfur of 1, oxyanions are also the one type of nucleophile that reacts with 1 at a rate closely comparable to their rate of reaction with PhSO2SPh. (3) All other types of nucleophiles are much less reactive toward 1 than they are toward the thiolsulfonate, the magnitude of the effect ranging from a factor of 20-40 for such nucleophiles as CN-, SO32-, and PhS- to a factor of 400-700 for common amines. It is suggested that the very low reactivity of amines (and azide ion) toward 1 may be the result of attack of the nucleophile not being the rate-determining step in these particular substitutions. © 1979, American Chemical Society. All rights reserved.