【摘要】 在 B3LYP/6-31 G* 水平上以二甲醚 ( Me2 O)模拟四氢呋喃 ( THF)对烯烃在 THF溶液中硼氢化反应的机理进行了研究 .计算结果发现 ,烯烃通过类似 SN2的交换过程从醚与 BH3构成的配合物获得 BH3结合成π配合物中间体 ,这一交换是整个硼氢化反应的决速步骤更多还原

【Abstract】 The reaction of the monomeric BH 3 with alkenes in ether media has been examined by using B3LYP, a hybrid density functional method, with 6 31G * basis set. Calculations of various possible species involved in the hydroboration process, including the complexes of borane (BH 3) with dimethyl ether, ethylene, propene, 1 butene, trans 2 butene, cis 2 butene, 2 methylpropene, 2 methyl 2 butene and 2,3 dimethyl 2 butene as well as the reactants and transition states of the corresponding hydroboration have been performed. The zero point energies(ZPE) and thermal analyses were computed at the same level. Based on the calculations, the prior formation of a three center π complex intermediate of BH 3 with the respective alkene is predicted and the overall reaction rate was determined. For the formation of the π complex intermediates, two extreme pathways, i.e . the S N1 and S N2 like manner, have been compared, with the latter one more preferentially in terms of the activation barrier by 25~28 kJ/mol endothermically.更多还原