Kinetics and mechanism of the hydrolysis of tetrahydro-2-furyl and tetrahydropyran-2-yl alkanoates

Abstract

The kinetics and mechanism of the hydrolysis of tetrahydro-2-furyl and tetrahydropyran-2-yl alkanoates in water and water–20% ethanol are reported. In acidic and neutral media, kinetics, activation parameters, ¹⁸O isotope exchange studies, substituent effects, solvent effects and the lack of buffer catalysis point clearly to an A_A1-1 mechanism with formation of the tetrahydro-2-furyl or tetrahydropyran-2-yl carbonium ion as the rate-limiting step. There is no evidence of a base-promoted B_AC-2 mechanism up to pH 12.