Nucleophilic Substitution at a Carbonyl Carbon Atom (). Solvolysis of 2-Furoyl Chloride and 2-Thenoyl Chloride in Binary Mixtures

[摘要] The kinetics of the solvolysis of 2-furoyl chloride and 2-thenoyl chloride in MeOH-H2O, EtOH-H2O, (Me)2CO-H2O, MeCN-H2O and MeCN-MeOH has been investigated. The rates were faster in protic solvents than in aprotic solvents. This was caused by the bond breaking of leaving group through hydrogen-bonding solvation of protic solvents. In MeCN-MeOH the rate in MeOH rich solvents was faster than in MeCN rich solvents by the specific solvation of alcoholic hydrogen and there was a maximum rate of reaction at MeOH mole fraction of 0.8. The reaction rates of solvolysis were considerably slower than those of benzoyl chloride owing to the electron withdrawing effect of thienyl and furyl groups. It was concluded that solvolytic reaction proceeds via a dissociative SN2 mechanism in which bond-breaking precedes bond-formation at the transition state.

[学科分类] 化学（综合）