Theoretical Studies On The Pyrolysis Mechanism Of N, N-Dimethylglycine Ethyl Ester And The Photodissociation Mechanism Of Hydroxyacetone

It is very important to determine the reaction mechanism in the chemical reaction. Currently, it is a major field of research in the computational and theoretical chemistry to investigate the chemical reaction and determine the reaction mechanism by using of ab initio calculation methods. In our studies, we have theoretically investigated the pyrolysis mechanism of N, N-dimethylglycine ethyl ester in the gas phase and the photodissociation mechanism of hydroxyacetone.Ab initio calculations at the MP2/6-31+G* level have been used to study the mechanism of N, N-dimethylglycine ethyl ester pyrolysis in the gas phase. The synchronicities have been calculated using Pauling bond orders. The results have shown that the reaction is a stepwise process. The first process is the decomposition of N, N-dimethylglycine ethyl ester to form N, N-dimethylglycine and ethylene, while the second process is the decomposition of N,N-dimethylglycine to yield trimethylamine and carbon dioxide. The first process is the rate-controlling step.The reaction pathways for CH3COCH2OH (hydroxyacetone) photo-dissociation on the low-lying electronic states have been studied with use of the CASSCF energy gradient techniques. The S0/S1 and S1/T1 intersection points were determined by the state-average CASSCF method. Two main reaction pathways,which are possible to the photodissociation, have been studied. It has been found that the mechanism is a stepwise and belongs to Norrish type-I reaction. The n→π excitation leads to the first excited singlet state, followed by the intersystem crossing from S1 to T1. On the T1 potential energy surface, the system can dissociate adiabatically to CH3(X) + COCH2OH(X) and CH3CO(X) + CH2OH(X). The COCH2OH(X) and CH3CO(x) radicals can further dissociate into CO, OH and other fragments.