Quantum Chemistry Study On The Reaction Of ROOO(R=H, CH₃) Radical With NO

The HOOO radical is of interest in many areas of chemistry,spanning from biochemistry to atmospheric science.More and more focus of research on HOOO stems from the experimental confirmation of the existence of HOOO by F.Cacace in 1999.All of these researches focus in the confirmation of the existence of the radical and the molecular geometry of the radicals.As far as we know,there is still no research on the reaction involving HOOO has been done.In this thesis,the mechanism of the reaction of hydroxyl radical ROOO(R=H, CH₃) with NO was investigated.The geometry,electron structure and chemical bond were studied by quantum chemistry methods and electron density topological analysis, and the reaction dynamics was analysed at Classical Transition state Theory.The results provided useful information on the reaction of the transient species ROOO(R=H,CH₃) with NO,this is helpful to understand the transformation of the radical in atmosphere.This thesis consists of six chapters as following.In the first chapter,a survey of experimental and theoretical studies on HO_x(x=1,2, 3) radicals that has been done is presented.In the second chapter,the development and applications of modern quantum chemistry theory and quantum topological theory were described briefly.In the third chapter,the reaction mechanisms of HOOO and NO on the singlet surface were investigated.Seven reaction channels have been found,and the product HO₂+NO₂ was determined to be the main channel.Microcosmic reaction mechanism of each channels have been discussed by topological analysis of electron density and the structure transition region and structure transition state have been found.The reaction energy of each reaction channels is very small,and the Structure Transition State and the Energy Transition State were separated very closely.In the fourth chapter,the reaction mechanisms of the reaction of HOOO with NO were proposed,and trans-HONO+³O₂ are determined to be the main products in all reaction channels.Microcosmic reaction mechanism and the variation of the chemical bond in each channel were discussed by topological analysis of electron density.In the fifth chapter,we discussed the isomerization of the intermediates complexes appeared in the reaction HOOO with NO on the singlet surface.As a result,the relation among the complex COM1,COM3,COM5 and COM6 has been found,and classified them into different sorts for discussing.In the last chapter,the reaction CH₃OOO with NO on the singlet surface has been discussed,and six channels have been found.Then we analyzed the dynamic character in all channels with Classical Transition state Theory,and conclude the second and the fourth channel are the main channels in reactions.The innovations of this work are listed as following: 1.The reaction mechanisms of HOOO radical with NO on both singlet and triplet surface have been studied.The main products of HO₂+NO₂ or HONO+¹O₂ were proposed on the singlet surface,and HO₂+NO₂ or HONO+³O₂ were found as main products on the triplet surface.This provide a deep understanding on the role of the transient species HOOO in atmospheric chemistry,and provide a channel that produce singlet oxygen in the atmosphere.2.The reaction mechanism of the reaction of HOOO radical with NO has also been studied by electron density topological analysis.The variation of the chemical bond and ring structure in both singlet and triplet channel has been discussed.The reaction energy is very low in the singlet channel,and the Structure Transition State and the Energy Transition State was found separated very closely.3.The reaction of CH₃OOO radical with NO in singlet channel has been studied,and HOONO+HCHO and CH₃OO+NO₂ were found to be the main products.It provides a possible source of formaldehyde(HCHO) and nitric acid(HOONO) that appears in the atmosphere.According to the Classical Transition state Theory, the dynamics of the six channels were analyzed,and it is concluded that the first and the fourth channels are main channel in reaction and it also affirmed that the first channel is more important in reactions.