Hydrogen Abstraction Reaction Mechanisms and Rate Constants for Isoflurane with a Cl Atom at 200～2000 K:A Theoretical Investigation

The kinetics and mechanisms of H abstraction reaction between isoflurane and a Cl atom have been investigated using DFT and G3（MP2） methods of theory. The geometrical structures of all species were optimized by the w B97XD/6-311++G** method. Intrinsic reaction coordinate（IRC） analysis has been carried out for the reaction channels. Thermochemistry data have been obtained by utilizing the high accurate model chemistry method G3（MP2） combined with the standard statistical thermodynamic calculations. Gibbs free energies were used for reaction channels analysis. Two channels were obtained, which correspond to P（1） and P（2）. The rate constants for the two channels over a wide temperature range of 200;000 K were also obtained. The results show that the barriers of P（1） and P（2） reaction channels are 50.36 and 50.34 k J/mol, respectively, predicting that it exists two competitive channels. The calculated rate constant is in good agreement with the experiment value. Additionally, the results also show that the rate constants also increase from 1.85×10-16 to 2.16×10-12 cm3·molecule-1·s-1 from 200 to 2000 K.