运用NMR和DFT研究Michael加成反应的动力学行为及反应机理:(CO)_5W=C(OEt)C_2Ph作为底物  

Mechanistic Studies on Michael Type Addition by NMR Technique and DFT Methods:(CO)_5W=C(OEt)C_2Ph as the Substrate

作　　者：顾开春[1] 杨刚[1] 张维萍[1] 刘秀梅[1] 余正坤[2] 韩秀文[1] 包信和[1] 

机构地区：[1]中国科学院大连化学物理研究所催化基础国家重点实验室,大连116023 [2]中国科学院大连化学物理研究所,大连116023

出　　处：《无机化学学报》2006年第6期1043-1048,共6页Chinese Journal of Inorganic Chemistry

基　　金：国家科技部资助项目(No.2003CB615806)。

摘　　要：利用核磁共振方法研究了取代吡唑对炔基Fischer卡宾化合物的Michael加成的动力学行为,该反应为典型的二级反应。当吡唑的3,5-位由较大基团取代时,反应速率常数变小,而活化焓和活化熵明显增大。利用密度泛函理论研究了炔基钨卡宾为底物的Michael加成反应机理,发现吡唑上取代基团的增大可以导致第三步反应的活化能大于第一步,从而使反应的决速步骤由原来的第一步转变为第三步。Kinetics of Michael type addition using alkynyl carbene complex as substituent was studied by ^1H NMR technique. To either substituted pyrazols or tungsten Fischer carbene, the reaction is of first order. And when the substituted groups at 3,5-positions become larger, the reaction rates slow down, with the obvious increase in activation enthalpies and entropies. Through density functional calculations, the mechanism of Michael type addition was investigated with alkynyl carbene complex as the substrate and 3,5-diphenyl-pyrazole （or 3,5-ditertbutyl-pyrazole） as the nucleophile. It of step 3, making it larger different from the Michael groups. was found that the large substituted groups will increase greatly the activation barrier than that of step 1. Acco reactions with pyrazoles rdingly, the rate-determining step should be step 3, which is containing smaller substituted groups or without substituted groups.

关 键 词：Fischer卡宾化合物 MICHAEL加成 核磁共振 密度泛函 机理 

分 类 号：O614.111[理学—无机化学] O614.112[理学—化学]