Thermal Isomerizations of Substituted Benzyl Isocyanides

초록

The absolute and relative rates of thermal rearrangements of substituted benzyl isocyanides were obtained at the temperatures between 170 and 230 ℃. The relative rates are independent of temperature and exhibit excellent Hammett correlations (ρ+ = -0.24). The temperature studies yielded activation parameters (ΔH≠Y and ΔS≠Y) and their differential counterparts (ΔΔH≠Y-H and ΔΔS≠Y-H). The differential terms were plotted against σ+. The secondary α-deuterium kinetic isotope effects (kH/kD = 1.11) were measured at several temperature. The rate data can be rationalized with the cyclic TS. The substituent effects on the rates are due to the entropic contributions.