Ab initio kinetic study on the low-energy paths of the HO + C ₂ H ₄ reaction

The low-energy paths for the reaction of HO with C₂H₄ have been studied at the PMP2/aug-cc-PVQZ//MP2/cc-PVTZ level of theory. The rate constants for the production of C₂H₄OH, CH ₂CHOH + H and C₂H₃ + H₂O calculated with variational RRKM theory indicated that below 500 K, the formation of C ₂H₄OH (k₁) via an OH ⋯ π complex with 1.9 kcal/mol binding energy is the major product channel exhibiting a negative-temperature dependence; between 800 and 1000 K, the formation of CH₂CHOH + H (k₂) and C₂H₃ + H ₂O (k₃) becomes competitive; at T > 1000 K, k ₃ becomes dominant. k₁ was found to be strongly affected by multiple reflections above the well of the OH ⋯ π complex. The predicted results are in close agreement with available experimental data.