AN EVALUATION OF VINYL HYDROPEROXIDE AS AN ISOLABLE MOLECULE

Ab initio molecular orbital calculations were carried along the reaction surface for the decomposition of vinyl hydroperoxide. Geometry optimizations were obtained at both the 6-31G* and MP2/6-31G* levels for vinyl hydroperoxide, the enol/alpha-carbonyl, and hydroxyl radicals, and the transition state structure that leads to these products. Energies for these species were determined by single-point MP4 calculations at the MP2/6-31G* geometry (MP4/MP2/6-31G*). Frequency calculations on these species provide the enthalpy and entropy of reaction and the activation energy at 298 K. From the calculated Arrhenius activation energy of 26.0 kcal/mol and log A values of 13.76 and 13.72 at 25 degrees C and 0 degrees C, respectively, the lifetimes of vinyl hydroperoxide at the these temperatures are estimated to be 58 and 3520 h. These calculations suggest that vinyl peroxides are reactive, but potentially isolable species under proper conditions. Spin density calculations and an analysis of calculated IR frequencies indicate that the odd electron is largely on carbon rather than oxygen in the enol/alpha-carbonyl radical.