Computational Mechanistic Study of the Gas Phase Oxidation of Methanol with Ozone

Abstract

The reaction of methanol and ozone on the singlet potential energy surface has been carried out using the RMP2 theoretical approach in connection with the 6-311++G(d, p) basis set. To obtain a more reliable energy, single point calculations were performed for all species at the CCSD(T) level. One prereactive complex C1 is formed between the reactants. From a variety of the complexes, five types of product are obtained, of which four types have enough thermodynamic stability at the RMP2 level. In the thermodynamic approach, the most favoured route begins with the formation of a pre-reactive complex C1 and gives H 2 CO + H 2 O + 3 O 2 as the final adducts. This process is exothermic by -73.243 kcal mol -1 in standard enthalpy and exergonic by -83.382 kcal mol -1 .

Barriometry – an enhanced database of accurate barrier heights for gas-phase reactions

“…Shayan and Vahedpour have explored the reaction between methanol and ozone on a singlet potential energy surface at the [CCSD(T)//MP2]/6-311++G(d,p) level. 42 The PES is quite complex with a pre-reaction complex, intermediates and products including CH 2 O, cis and trans dihydrogen trioxide or trioxidane, H 2 O 3 , and methanediol, CH 2 (OH) 2 . However what is of particular interest here is that the barrier heights which lead eventually to CH 2 O + cis-H 2 O 3 and to CH 2 O + trans-H 2 O 3 of 123 and 141 kJ mol À1 at the MP2 level being completely reversed at CCSD(T) to 183 and 91 kJ mol À1 , respectively.…”

The atmospheric relevance of primary alcohols and imidogen reactions

“…In the atmosphere and interstellar space, the most predominant non-methane organic species is methanol 10 – 12 , which is the main source of tropospheric CO 13 and formaldehyde 14 , and also has small action in the tropical HOx and ozone budgets 15 , 16 . Methanol is emitted into the atmosphere by several sources such as vegetation 17 , 18 , plant growth 19 , 20 , biomass burning, biofuels 21 , 22 , plant matter decay 23 , 24 , and human activities in urban and industrial regions 25 .…”