The Theoretical Investigation For The Reactions Of Unsaturated Alcohol, Halogenated Olefins And Thiophene With Active Free Radicals

Series of unsaturated alcohol, halogenated olefins(such as CH2=CHCH2OH, CH≡CCH2OH, CH2=CHCH2F and CH2=CHCH2Cl and so on) and thiophene are a kind of important unsaturated volatile organic compounds(VOCs), and widely exist in the air, and they have a profound effect to the atmospheric environment. These two kind of compounds play an important role in the formation process of Secondary Organic Aerosols(SOA). SOA seriously affect the atmospheric visibility, climate change, human health, tropospheric chemistry and so on. Therefore, it is very important for these two kind compounds to be translated and absorbed, in which the dominant degradation pathway is the reactions with radicals(e.g., OH, O, NO3). Because these reactions are very complex and could generate many small molecules and free radicals, it is difficult to research these reaction in experiment. In theoretically, it is particularly important to choose the appropriate calculation method. In this paper, using quantum chemistry theories and methods to research the mechanism of unsaturated alcohol and unsaturated halogenated with active free radicals, and calculate rate constants. The calculated results are compared with experimental values, and provided some theoretical prospect.In this paper, the main research results are as follows:The first chapter The mechanism and kinetic of CH2=CHCH2OH+OH and CH≡CCH2OH+OH had been investigated using quantum chemistry methods. We optimized the geometries at MP2/6-311++G(d,p) level, and calculated the single point energies for CH2=CHCH2OH+OH using G3(MP2) method; as for CH≡CCH2OH+OH, MP2/cc-p VTZ was used to optimize the geometries, and CCSD(T) method was used to calculate the single point energies. We get the final products and the most favorable pathways. The calculated results revealed tha OH radical associated with the C=C or C≡C of CH2=CHCH2OH and CH≡CCH2OH moleculars forming the pre-reactive complex firstly, and then formed the corresponding intermediates, respectively. Due to the higher energies of these intermediats, they can occur the further isomerization and decomposition pathways to generate the final products. Based on the potential energy surface information, the kinetics of these two reactions were studied using the transition state theory(TST) and multichannel RRKM methodologies over the whole temperature range of 200-3000 K and pressure-range of 10-14-1014 Torr.The second chapter Along with the investigation of CH2=CHCH2OH+OH and CH≡CCH2OH+OH, we detailed studied the reaction of CH2=CHCH2Cl+OH and CH2=CHCH2F+OH, respectively. We get the geometriesand rnergies of the reactants, intermediates, transition state, pre-reactive complex and products, an building the detailed potential energy surface information. Because CH2=CHCH2Cl and CH2=CHCH2F are both unsaturated compounds, these two reactions are also similar with the reaction of OH wih C2H4 or CH3CH=CH2, the entrance of these two reactions exist pre-reactive complex, and are both barrierless processes. We used the RRKM theory calculated the rate constants, and compared with the experimental values. We found that the calculated rate constants were in good agreement with available experimental data over the temperature range, indicating our calculation results are reliable. We also carried out the reliable theoretical prediction without measuring the temperature rang of the experiment. At 200-300 K,we get the temperature- and pressure-dependent rate constants, and the branching ratio of the important reaction channels. This may be help us to better understand this kind of reaction micro reaction mechanism and provide theoretical basis for future study.The third chapter It is the first time to study the mechanism of the reaction of thiophene and OH. On the potential energy surface, two kinds of reaction mechanism were revealed, namely, direct hydrogen abstraction: OH radical abstracted the hydrogen atom of the α(C2) or β(C3) site of thiophene to produce H2O+2-thienyl or H2O+3-thienyl, respectively;addition/elimination:OH radical added to the α(C2) or β(C3) site of thiophene to generate the rich energy intermediates, subsequently, these intermediates occur the further decomposition processes produce the final products. The rate constants for the reaction of OH with thiophene had been employed by using RRKM statistical rate theory, and compared with the experimental values. At 100 Torr with Ar as bath gas, OH add to the α(C2) forming intermediate IM1 and P1 were the major pathways in the temperature range of 200-400K; at 400-800 K,P1 was the major product; at high temperature range of 800-3000 K, at high temperature range(800-3000K), the production of H2 O and 3-thienyl via hydrogen abstraction became dominant.