Mechanism and kinetics of the production of hydroxymethyl hydroperoxide in ethene/ozone/water gas-phase system

Abstract

The mechanism and kinetics of the production of hydroxymethyl hydroperoxide (HMHP) in ethene/ozone/water gas-phase system were investigated at room temperature (298±2 K) and atmospheric pressure (1×105 Pa). The reactants were monitored in situ by long path FTIR spectroscopy. Peroxides were measured by an HPLC post-column fluorescence technique after sampling with a cold trap. The rate constants (k 3) of reaction CH2O2+H2O→HMHP (R3) determined by fitting model calculations to experimental data range from (1.6−6.0)×10−17 cm3·molecule−1·s−1. Moreover, a theoretical study of reaction (R3) was performed using density functional theory at QCISD(T)/6-311+(2d,2p)//B3LYP/6-311+G(2d,2p) level of theory. Based on the calculation of the reaction potential energy surface and intrinsic reaction coordinates, the classic transitional state theory (TST) derived k 3 (k TST), canonical variational transition state theory (CVT) derived k 3 (k CVT), and the corrected k CVT with small-curvature tunneling (k CVT/SCT) were calculated using Polyrate Version 8.02 program to be 2.47×10−17, 2.47×10−17 and 5.22×10−17 cm3·molecule−·s−1, respectively, generally in agreement with those fitted by the model.