Kinetics Studies on Nucleophilic Reactions of Methanesulfonyl Chloride with Substituted Aniline in Methanol

[摘要] Rates of reactions of methanesulfonyl chloride with various substituted anilines have been measured in methanol. Substituent effects in aniline are found to be linearly correlated with pKa(Br¥õnsted relation with ¥â = 0.84) and ¥ñ(Hammett equation with ¥ñ = -2.46) respectively. The results are interpreted in terms of degree of bond-formation at the transition state, which was found to have progressed relatively further. The rates for o-methylaniline deviated from the Br¥õnsted plot established by meta and para substituted anilines because of a steric effect of ortho position in aniline. Activation parameters, ¥ÄH¡Á and ¥ÄS¡Á have also been determined. The enthalpy of activation showed a regular variation in that electron donating substituents in the p-substituted aniline decrease ¥ÄH¡Á and increase the negative value of ¥ÄS¡Á.

[学科分类] 化学（综合）