用密度泛函方法研究N-甲基吡咯烷酮与二硫化碳的反应

N-甲基吡咯烷酮（NMP）和二硫化碳（CS₂）在加压下发生热反应生成N-甲基吡咯烷-2-硫酮.用密度泛函方法确定了该反应有两条平行的路径，获得了相关的4个过渡态和2个中间体的构型；在拟定了两步反应机理的基础上，确认了第一步反应为速度控制步骤，计算了在298K和500K下两种反应路径的活化能和速率常数.根据计算结果判断NMP羰基的α氢原子通过与羰基氧的分子内相互作用在反应中起重要作用，同时确认了反应区域为NMP的羰基碳和氧、α位上的碳和氢，以及CS₂中的碳原子和其中的一个硫原子所构成的两个并联的四元环.

STUDY ON REACTION OF N-METHYL-2-PYRROLIDINONE WITH CARBON DISULFIDE USING DENSITY FUNCTIONAL THEORY

Thermal reaction of N-methyl-2-pyrrolidinone(NMP) and carbon disulfide(CS₂) under elevated pressure leads to the formation of N-methylprrolidine-2-thione. Using density functional theory, two parallel paths of the reaction and related configurations of 4 transition states and 2 intermediates were determined. The two-step reaction mechanism was suggested and the first step was confirmed to be rate determining step. Based on the mechanism, the kinetic parameters were calculated. At 298 K, the activation energy values of path 1 and path 2 were 604.740 and 598.101 kJ•mol^-1 respectively; at 500 K, they were 607.665 and 601.055 kJ•mol^-1. The corresponding rate constants were 1.90×10^-105, 3.81×10^-104, 4.33×10^-66 and 4.70×10^-60m³•mol^-1•s^-1, respectively. According to the calculation data， it was concluded that the α-H atom near carbonyl group of NMP played an important role in the reaction via intramolecular interaction with carbonyl O atom and the reaction region was two tetratomic rings that connected with each other, and consisted of carbonyl C and O, α-C and H of NMP, in addition to C and S in CS₂.