气态丙烯酸光致脱羧反应AM1法研究

AM1 STUDY OF THE PHOTODECARBOXYLATION REACTION OF ACRYLIC ACID IN THE GAS PHASE

半经验的自洽场分子轨道法（ＡＭ１）被用来研究激发单态（＾１ππ＾＊）和三态（＾３ππ＾＊）丙烯酸的脱羧反应。计算结果支持Ｒｏｂｅｒｔ等人提出的光解机理。与实验结合，进一步推测，丙烯酸光致脱羧反应的第一步，是沿单态途径进行，第二步沿三态途径进行。单态和三态反应途径中的反应物、过渡态、中间体和产物都用能量梯度技术进行了优化。对于过渡态和中间体，还作了振动分析，确证它们分别是一级鞍点和能量极小值点。

In this parper,the decarboxylation reaction of acrylic acid in the singlet and triplet excitedstates were investigated by semi-empirical self-consistent-field molecular orbital method(AM1).Our results support the mechanism of photolysis proposed th Robert.In combintion with ex-periment,it can be deduced that the first step of photodecarboxylation reaction is in the singletpathway,the second step in triplet pathway.The reactants,transition states,reaction intermedi-ates and products corresponding to the singlet and triplet pathways were optimized by gradienttechniques.All of the transition states and intermediates were confirmed by full vibrational anal-ysis.