Theoretical Investigation Of The Reaction Mechanism Of Atomic Oxygen Radical Anion With Pyridine And Ethanol

The main job of this dissertation is to investigate the reaction mechanism of Oˉ+ C5H5N and Oˉ+ C2H5OH using G3MP2B3 theretical method. Possible thermodynamic reaction pathways are predicted and vivid reaction mechanisms are displayed. Based on our calculation results, previous experimental results of the two reaction systems are explained properly, and more information is obtained for further studies.1. Three different entrance potential energy surfaces of Oˉ+ C5H5N are explored respectively as atomic oxygen radical anion attacksγ-,β- andα-H atoms in pyridine. Possible thermodynamic product channels are examined subsequently. Based on the calculated G3MP2B3 energies and optimized geometries of key species on the reaction potential energy surfaces, it has been demonstrated that the oxide anion formation channel is dominant, and the H2+-abstraction channel is also favorable in thermodynamics, whereas the H-abstraction and H+-abstraction channels are inaccessible at room temperature.2. As atomic oxygen radical anion attacks the hydroxylic H atom,α-H andβ-H in ethanol respectively, the reaction potential energy surface of Oˉ+ C2H5OH has been deeply investigated. Several product channels are illustrated, and the following results are obtained: the hydroxylic H+-transfer channel (1), the hydroxylic H-transfer channel (2) and enolate anion formation channel (5) are main product channels. Theβ-H transfer channel (4) is also available in thermodynamics. Besides, theα-H transfer channel (3) is also confirmed possible through the classical trajectory calculations of TS6a and TS6b, which are the initial transition states formed by Oˉapproachingα-H atom. Based on the results of the BOMD classical trajectory calculations, the main products of TS6a and TS6b are the IRC-products (with H2O formed), and only a small part of H abstraction products are obtained. Thus the product branching ratio of theα-H transfer channel (3) is very small. Apart from these anion product channels, three electron formation channels are also displayed, which can not be detected in experiments.