丙烯醛及其衍生物基态脱羰反应机理的理论研究

Theoretical Study on Decarbonylation Reaction of Acrolein and Its Derivatives in Their Electronic Ground States

用从头算自洽场分子轨道方法和能量梯度技术，研究丙烯醛及其衍生物基态脱羰反应的机理，用二级微扰方法考虑电子相关效应．结果表明基态丙烯醛脱羰为一简单反应，反应涉及三中心过渡态．取代基对丙烯醛脱羰反应仅有较小的影响，从计算的势垒可以推得基态丙烯醛及其衍生物热脱羰是很困难的，但是，光激发得到的丙烯醛很可能首先通过内转换成系间窜跃回到基态，然后发生脱羰反应，即基态脱羰很可能在其光解离反应机理中起着重要作用．

In this paper, decarbonylation reaction of acrolein and its derivatives in their electronic ground states were investigated by restricted Hartree-Fock SCF method with energy gradient technique at the level of 3-21G basis set. Electron correlation was considered at the second-order perturbation level. It has been found that decarbonylatio reaction of acrolein is a simple reaction involving a three-centered transiton state which has been ascertained by frequency analysis. The potential barrier of decarbonylation reaction of acrolein is 435.1kJ·mol-1, the substituting groups have a little influence on the potential barrier of reaction. The decarbonylation reactions of acrolein and its derivatives in their electronic ground states are difficult to take place, but the ground-state decarbonylation probably plays an important role in the mechanisms of the photo-decarbonylation of acrolein.