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应用Gaussian 09程序,在MP2/6-311+G(2d,2p)理论水平下,对CH3F和H2O反应体系的反应机理进行研究,发现2个反应通道,通道1是CH3F和H2O首先形成复合物CH3F·H2O,然后经过过渡态TS(CH3…F…HOH)直接生成产物CH3OH和HF;通道2是CH3F先经过过渡态TS’(H2C…HF+H2O)形成中间产物P1(H2C·OH2+HF),然后经过过渡态TS’’(H2C…OH2+HF)生成产物CH3OH和HF。TS、TS’、TS’’分别为68.120,88.422,85.215 kcal/mol,TS比TS’约低20 kcal/mol,即通道1为主要反应途径。研究CH3X(X=F,Cl,Br,I)和nH2O(n=1,2)的反应规律性,对Br、I使用Lan12mb赝势基组。结果表明:CH3X与1H2O反应时,CH3F、CH3Cl、CH3Br、CH3I的反应能垒TS分别为66.635,63.384,61.774,56.254 kcal/mol,随着卤原子序数增加,反应能垒降低约3 kcal/mol。CH3X和2H2O反应时,CH3F、CH3Cl、CH3Br、CH3I的反应能垒TS1分别为57.264,54.084,51.389,39.816 kcal/mol;CH3F、CH3Cl、CH3Br的TS1比TS低10 kcal/mol左右,而CH3I的TS1比TS低16.4kcal/mol。CH3F水解的活化能TS1为57 kcal/mol,与实验值吻合较好。
The reaction mechanism of CH3F and H2O reaction system was studied under the theoretical level of MP2 / 6-311 + G (2d, 2p) using Gaussian 09 program. It was found that the two reaction channels, CH3F and H2O, were the first to form complex CH 3 F · H 2 O, and then directly through the transition state TS (CH 3 ... F ... HOH) to generate the products CH 3 OH and HF directly; channel 2 CH 3 F first through the transition state TS ’(H 2 C ... HF + H 2 O) ) And then the product CH3OH and HF via the transition state TS “(H2C ... OH2 + HF). TS, TS ’and TS ”were 68.120, 88.422 and 85.215 kcal / mol, respectively. TS was about 20 kcal / mol lower than TS’, that is, channel 1 was the main reaction pathway. The reaction regularity of CH3X (X = F, Cl, Br, I) and nH2O (n = 1,2) was studied. For the Br and I, the Lan12mb pseudopotential base was used. The results show that the reaction barriers TS of CH3F, CH3Cl, CH3Br and CH3I are 66.635, 63.384, 61.774 and 56.254 kcal / mol, respectively. When the number of halogen atoms increases, the energy barrier of reaction decreases by about 3 kcal / mol . The reaction barriers TS1 of CH3F, CH3Cl, CH3Br and CH3I are 57.264, 54.084, 51.389 and 39.816 kcal / mol for CH3X, CH3Cl and 2H2O, respectively. TS1 of CH3F, CH3Cl and CH3Br is about 10 kcal / mol lower than TS, TS1 is 16.4 kcal / mol lower than TS. The activation energy TS1 of hydrolysis of CH3F is 57 kcal / mol, which is in good agreement with the experimental data.