采用密度泛函理论B3LYP/6—31G(d,p)方法研究了2-(2-甲基丙烯基)-3-(3-甲基-1,2-丁二烯基)环己-2-烯酮重排生成八元环化合物在气相中的反应机理.考虑了两条可能的反应途径:途径1包含5个过程,途径2包含两个过程.从能量上看,两条途径的决定速度步均是[1,5]氢迁移.采用自洽反应场极化连续模型(PCM模型)和极化导体模型(CPCM模型)研究了反应体系在甲苯溶液中的溶剂效应.结果表明,气相和溶液中途径2均是较优途径,并且甲苯对该反应的溶剂化效应不明显.理论研究结果与实验观察结果一致,并很好地解释了有关实验现象.
The sequential rearrangement mechanism from the 2- (2-methylallyl) -3- ( 3-methylbuta- 1,2-dienyl) cyclohex-2-enone to form eight-ring membered compounds was studied at the B3LYP/6-31G(d,p) level. Two pathways were considered. The first pathway includes five processes while the second pathway undergoes only two processes. Both the two pathways have the same rate determining step of the [ 1,5 ] -hydrogen migration. In addition, the effect of toluene solvent was assessed by the polarizable continuum model. The calculation results indicate that the second pathway is favorable both in the gas phase and in toluene solvent.