Mechanisms and rate constants in the atmospheric oxidation of saturated esters by hydroxyl radicals: A theoretical study

作者：Cordova Gomez Moises^*; Iuga Cristina; Raul Alvarez Idaboy Juan

来源：International Journal of Quantum Chemistry, 2012, 112(21): 3508-3515.

DOI：10.1002/qua.24149

• kinetics
• branching ratios
• hydrogen abstraction

In this work, we have performed quantum chemistry and computational kinetics calculations to study the OH radical initiated oxidation of four saturated esters: methyl formate, ethyl formate, ethyl acetate, and n-propyl acetate. All possible mechanisms have been considered, and rate constants have been calculated using Conventional Transition State Theory. Systematic branching ratios for the different paths contributing to the overall reaction, at 298 K, are reported. In all cases, the calculated overall rate coefficients are in excellent agreement with reported experimental data, thus supporting the proposed mechanisms. The different site reactivity is rationalized in terms of the activation by different groups present in each molecule. The order of site reactivities for H abstraction was found to be ?OCH2? %26gt; ?CCH2? %26gt; HC(O)O? %26gt; ?OCH3 %26gt; CH3C(O)O?. This order explains the observed rate constants in the studied esters and can be extrapolated to similar compounds. The role of hydrogen bond-like interactions in the transition states and their influence on the observed site reactivities is discussed.

• 出版日期2012-11-5