Theoretical studies on the gas phase reaction mechanisms and kinetics of glyoxal with HO_2 with water and without water

摘要

The quantum chemical methods are employed to investigate the reactions of glyoxal with the HO_2 radical and the HO_2 and H_2O. There are twelve complexes found herein, whose stabilized energies are in the range of -3.8kcal/mol to -12.3kcal/mol. The calculated results predict that the proton coupled electron transfer process is the most favorable in the reactivity of the HO_2 radical with glyoxal due to the low energy barrier of 5.4kcal/mol. In addition, the barriers in the reaction glyoxal with the formed HO_2...H_2O complex are so high that the processes are unlikely to occur in the atmosphere, whereas the energy barriers of the HO_2 reaction with the complexes formed between glyoxal and water are decreased. Additionally, the rate constant of the proton coupled electron transfer process is computed to be 2.83 × 10~(-16) cm~3 moleclue~(-1) s~(-1) at 298K using the transition state theory with Eckart correction, which agrees well with the experimental data. It is noted that the rate constants of the water-catalyzed glyoxal reaction with HO_2 is increased about 10 times greater than the naked reaction HO_2+(CHO)_2.