甲苯-2,4-二异氰酸酯与仲胺类化合物反应中的质子转移过程

采用密度泛函理论B3LYP/6-31+G(d，p)方法研究了甲苯-2，4-二异氰酸酯(2，4-TDI)与仲胺类化合物反应过程中的质子转移效应. 研究发现甲醇分子对反应有显著的催化效应，可使反应能垒大幅降低，这表明含活泼氢的化合物会加速质子转移过程，从而加快反应速率. 2，4-TDI与甲基-N-甲基氨基甲酸酯的催化加成反应为一步反应，其反应过渡态呈六元环结构；而2，4-TDI与N-甲基对硝基苯胺、二苯胺、1，2-二氢-2，2，4-三甲基喹啉等芳香胺类化合物的催化加成反应经历了两步反应，其中第一步为速率控制步骤. 研究表明，在与2，4-TDI的反应中，芳胺化合物的活性高于甲基-N-甲基氨基甲酸酯的活性，计算的反应活性顺序与实验结果一致.

Proton Transfer in Reaction between 2,4-Diisocyanatotoluene and Amine Compounds

The effects of proton transfer on the reaction between 2,4-diisocyanatotoluene (2,4-TDI) and active-hydrogen-containing amine compounds were calculated using density functional theory (DFT) at the B3LYP/6-31+G(d, p) level. The energy barriers are significantly reduced when a methanol molecule serves as a proton transporter or a reactive catalyst, indicating that the labile hydrogen-containing compound plays a key role in accelerating the reaction rate and proton transfer. The catalytic addition of 2,4-TDI and methyl N-methylcarbamate follows a one-step mechanism, with a transition state characterized by a sixmembered ring. However, the catalytic additions of 2,4-TDI and aromatic amines such as N-methyl-p-nitroaniline, diphenylamine, and 1,2-dihydro-2,2,4-trimethylquinoline involve two steps, with the first step as the rate-limiting step. The reactions between 2,4-TDI and aromatic amines have lower energy barriers than that between 2,4-TDI and methyl N-methylcarbamate. The aromatic amines are more active than methyl N-methylcarbamate in the reaction with 2,4-TDI, which is in a good agreement with experimental results.