Density functional theory (DFT) with B3LYP function was employed to study the mechanism of 2-(1-propinyl) -2' -acetylbiphenyl intramolecular cyclization reaction. The calculation results show that the re-action can occur through both the four-membered and the eight-membered ring pathways with FeCl3 catalyst or without catalyst. Under the two conditions, the rate determining steps of the two pathways are the processes of the formations of the four-membered ring intermediate and the eight-membered ring intermediate, respectively. Without the catalyst, the difference of the energy barriers of the rate determining steps of the two pathways of the reaction is only 6. 8 kJ · mol-1 , which exhibits that the two pathways are competitive. Under the existence of FeCl3 catalyst, the energy barrier of the rate determining step of the four-membered ring pathway is reduced to 137. 52 kJ·mol-1 ,which is 57. 4 kJ·mol-1 lower than that of the energy barrier of the eight-membered ring pathway. The low energy barrier shows clearly that the reaction catalyzed by FeCl3 occurs mainly through the four-membered ring pathway. Besides, the energy barrier of the rate determining step of the four-membered ring pathway with FeCl3 is 114. 23 kJ·mol-1 lower than that of the reaction without catalyst. These differences indi-cate that FeCl3 is an efficient catalyst which can increase the reaction rate and moderate the reaction condition.%采用密度泛函理论的B3LYP方法研究了2-(1-丙炔基)-2'-乙酰基联苯分子内环化生成菲衍生物的反应机理.结果表明,该反应在无催化剂和FeCl3催化下均能通过四元环和八元环路径生成产物,其相应的决速步骤分别为四元环和八元环的生成过程.在无催化剂时,四元环路径和八元环路径的决速步骤的能垒相差仅6.8 kJ·mol-1,两条路径为竞争反应.在FeCl3催化下,四元环路径决速步骤的能垒为137.52 kJ·mol-1,比八元环路径的低57.4 kJ·mol-1,为优势反应路径.该能垒比没有催化剂时低114.23 kJ·mol-1,表明FeCl3对于该反应具有强的催化作用,能够有效地提高反应速率,使反应在温和的条件下进行.
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