Nucleophilic Displacement at a Carbonyl Carbon Atom (). Methanolysis of Thiochloroformate in CH3OH-CH3CN Mixtures

[摘要] Methanolysis rate constants were determined for CH3O(CO)Cl, CH3S(CO)Cl and CH3S(CS)Cl in CH3OH-CH3CN mixtures. Results show that the rates are not predominantly influenced by the bulk solvent properties but are partly influenced by specific electrophilic solvation.Polarity of the solvent is not a dominant factor but it nevertheless plays a role in charge stabilization of the SN1 like transition state. The methanolysis proceeds through SN1 mechanism for CH3S(CS)Cl, for which both specific solvation of leaving group by methanol and charge stabilization by a high dielectric medium are important, while for CH3O(CO)Cl methanolysis occurs via SN2 mechanism in which both of the solvent effects are unimportant.

[学科分类] 化学（综合）