DIOXIRANE CHEMISTRY .23. THE EFFECT OF SOLVENT ON THE DIMETHYLDIOXIRANE EPOXIDATION REACTION

Second order rate coefficients for the epoxidation of trans-ethyl cinn amate (3) and cyclohexene (4) by dimethyldioxirane have been obtained in a number of binary solvents. These data were treated by the Kamlet- Taft multi-parameter solvent effect equation. These analyses indicate that solvents with hydrogen bond donor capacity (HBD) increase the rat e of these reactions while solvents with hydrogen bond acceptor (HBA) capacity decrease the rate. Variable temperature rate determinations f or the cyclohexene epoxidation permitted the calculation of E(a), log A, and transition state parameters for several solvent systems. These data also support the favourable effect of HBD solvents on the rate of epoxidation by dimethyldioxirane.