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采用密度泛函理论(DFT)中的B3LYP方法对CuI/BtH催化苯硫酚与对甲氧基溴苯C–S偶联合成(4-甲氧基)(苯基)硫醚反应机理进行了理论研究.在6-31+G(d)基组水平上,全参数优化了气相条件和N,N-二甲基甲酰胺(DMF)溶剂化条件下反应机理中所有反应物、过渡态、中间体和产物构型,对优化后各化合物的构型在B3LYP/6-311++G(d,p)基组下进行了单点能计算和零点能矫正,通过能量和振动频率分析以及内禀反应坐标(IRC)计算证实了中间体和过渡态的合理性.并且在优化计算相同基组水平上,应用自然键轨道(NBO)理论和分子中的原子(AIM)理论分析了复合物的成键特征和轨道间相互作用.在CuI单独催化此反应的机理中,计算得到一条反应路径,控制步骤所需活化能是180.49 kJ/mol(sol).而当CuI/BtH共同催化反应时,计算得到两条反应通道IA和IB,其中IA为最优反应通道,控制步骤所需活化能为101.77kJ/mol(sol);IB反应通道控制步骤活化能为143.78 kJ/mol(sol).配体苯并三唑(BtH)加入反应有效地降低了反应控制步骤所需活化能,同时有利于产物和催化剂的分离,这与实验所得结论一致.
The reaction mechanism of CuI / BtH catalyzed coupling of thiophenol and p-methoxybenzyl bromide C-S to (4-methoxy) (phenyl) sulfide was studied by B3LYP method in density functional theory Theoretical Studies. All the reactants and transition states in the reaction mechanism under gas phase conditions and N, N-dimethylformamide (DMF) solvation conditions were optimized at the 6-31 + G (d) basis set level, Intermediates and product configurations. The single point energy and the zero point energy can be corrected under the B3LYP / 6-311 ++ G (d, p) basis. The energy and vibrational frequencies of Intrinsic Reaction Coordination (IRC) calculations confirm the rationality of intermediates and transition states, and at the level of the same basis set for optimization calculation, the complex is predicted by the theory of natural bond orbital (NBO) and atom in molecule (AIM) And the orbital interaction between CuI and BtH.In the mechanism of CuI alone catalyzing this reaction, a reaction path was calculated, and the activation energy required for the control step was 180.49 kJ / mol (sol) .When CuI / BtH co-catalyzed the reaction , Two reaction channels IA and IB were calculated, IA was the optimal reaction channel, and the activation energy required for the control step was 101.77 kJ / mol (sol). The activation energy of the IB reaction pathway was 143.78 kJ / mol (sol). The addition of the ligand benzotriazole (BtH) effectively reduced the activation energy required for the reaction control step and facilitated the separation of the product from the catalyst The experimental conclusion is consistent.