Atmospheric Ch <sub> 3 </ Sub> N Series Oxide Reaction Process, Quantum Chemistry And The Electron Density Topological Study

In this thesis, CH₃N, CH₃NO and CH₃NO₂ are studied by using quantum chemistry methods and electronic density topological analysis method. In order to make the source of acid rain further clear and make something for the elimination of acid rain, the configurations of CH₃NO and CH₃NO₂ in atmosphere are predicated, and the microcosmic dissociation reaction mechanism of CH₃NO₂ are studied. All the studies are introduced in three parts, the first part shows the studies of the microcosmic reaction mechanism of CH3N with O and O₂, the second part shows the isomerization reactions of CH₃NO and the reactions of CH₃NO with O atom, and the last part shows the isomers and the dissociation reaction of CH3NO2.With the advancement of the technology, all kinds of industries developed rapidly, and the atmosphere pollution is becoming one of the ten problems that threaten our human. More and more scientists pay their attention to the nitrogen and oxygen containing compounds because of their donation to acid rain and their relationship to photochemistry in troposphere. CH₃N is one of the simplest organic radial and is considered as an instant intermediate in many combustion reactions, further more it is one of the most important radial inducing photochemical smog. The dissociation products of CH₃NO and CH₃NO₂ maybe the important source of acid rain because of containing NO_x. So our series of studies on CH₃N, CH₃NO and CH₃NO₂ have much significance. All of the studies on our system are carried out at 6-31 lG(d,p) level by using B3LYP, MP2(full), CCSD(t), QCISD and CASSCF methods.At the beginning of this thesis, the previous research studies on our system are surveyed. We present an introduction to the previous experimental and theoretical studies on CH₃N, CH₃NO and CH₃NO₂ inside and outside our country in chapter one.In chapter two, the development and wide application of modern quantum chemistry theory and quantum chemistry topological theory are described briefly. The application area of quantum chemistry is increasingly growing, bonding characters and electronic structures in molecule are still the main area of quantum chemical research work, because the electronic density topological analysis method is a new method, and its theoretical predictive ability is becoming more and more obvious. There are many studies need to be done by using this theory, and noteworthy achievements have been gained on the studies of bonding characters and reaction mechanism by using quantum chemistry topological theory over these years.The main part of the thesis begins with detailed studies on the microcosmic reaction mechanism of CH₃N and its isomer CH₂NH with O and O₂ respectively in chapter three. Three reaction channels are found when CH3N and its isomer CH₂NH react with O: O atom attacks the N atom in CH3N and CH₂NH and attacks the C atom in CH₂NH, and then CH₃NO, CH₂NHO and OCH₂NH form respectively; Two reaction channels are found when CH₃N and CH₂NH react with O₂: the O atom in O₂ molecular attacks the N atom in CH₃N and CH₂NH, CH3NOO and CH₂NHOO form respectively. The microcosmic mechanism and the bonding characteristics and the variation rules on the reaction pathways are discussed by using electronic density topological analysis method.In chapter four, the possible isomers in atmosphere of CH3NO are studied, twenty three isomers and all the transition states of the isomerization reactions are optimized, their reciprocal transformation among the isomers are made clearly, and therefore the possible geometries of CH3NO in atmosphere is predicted theoretically. The reactions of CH₃NO with O atom are studied in detail, and the changing rules of the bonds on the reaction pathways are analyzed by using electronic density topological analysis method.In chapter five, the possible isomers of CH₃NO₂ are studied by using CASSCF(4,4) and B3LYP methods at 6-311G(d,p), and the possible isomers of CH₃NO₂ in the atmosphere are predicted theoretically, seven reaction channels and seven isomers and an intermediate are discussed, the four of the isomers are new that have not been reported yet; the dissociation reactions of CH₃NO₂ and CH₃ONO on the single and triple potential energy reaction surfaces are studied also, there are four and three dissociation channels are found on singlet state and triplet state respectively, the microcosmic reaction mechanism and the changing rules of net charges and chemical bonds on the reaction pathways of above-mentioned dissociation reactions are studied by using electronic density topological analysis method.The novel conclusions and ideas of this work are listed as follows:1. Three reaction channels are found when CH₃N and its isomer CH₂NH react with O: O attacks the N atom in CH₃N and CH₂NH and attacks the C atom in CH₂NH, CH₃NO, CH₂NHO and OCH₂NH form respectively. Two reaction channels are found when CH₃N and CH₂NH react with O₂: O atom in O₂ attacks the N atom in CH₃N and CH₂NH, CH₃NOO and CH₂NHOO form respectively. The above-mentioned reactions...