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本文用 SCF MO ab initio法研究了甲醇与雷酸的亲核加成反应。所有计算采用 STO-3G基组。反应物、产物及过渡态的结构均进行了全优化。过渡态的结构通过其力常数矩阵有唯一负本征值而得到确证。雷酸在甲醇分子的诱导下易发生E式变型。这种变型决定了反应的立体化学性质,使五员环状氢键活化络合物得以形成,质子从甲醇氧转移到雷酸氧原子上发生在过渡态形成之时或之后。这种质子转移不需活化能,两个氧原子的适宜取向及电荷的转移促进了质子的“滑动”。整个反应为一步进行的放热反应。
In this paper, the nucleophilic addition reaction of methanol and acid was studied by SCF MO ab initio method. All calculations use the STO-3G basis set. The structures of reactants, products and transition states were fully optimized. The structure of the transition states is corroborated by a unique negative eigenvalue of the force constant matrices. Ray acid in the methanol molecule induced easy to E-type variants. This modification determines the stereochemistry of the reaction so that a five-member cyclic hydrogen bond activating complex is formed. The transfer of protons from the methanol oxygen to the atom of the oxygen atom occurs at or after the transition state is formed. This proton transfer does not require activation energy, and the proper orientation of the two oxygen atoms and the transfer of charges promote the “sliding” of the protons. The whole reaction is a one-step exothermic reaction.