合成甲氧苄胺嘧啶缩合反应产物中两种同分异构体的结构和稳定性的理论研究

Theoretical study of structure and stability of two isomers in condensation product in synthesizing trimethoprim

运用Gaussian03程序,采用B3LYP方法,取6-311G(d,p)基组,研究以三甲氧基苯甲醛为原料,制备甲氧苄胺嘧啶的缩合反应产物中两种同分异构体——2-甲氧甲基-3-(3,4,5-三甲氧基苯基)丙烯腈(Ⅰ)和2-(3,4,5-三甲氧基苄基)-3-甲氧基丙烯腈(Ⅱ)的结构和稳定性,通过结构和轨道能量分析,得化合物Ⅱ比化合物Ⅰ稳定性强的结论,与实验结果一致。

In the condensation of 3,4,5-trimethoxy benzaldehyde to synthesize trimethoprim（ TMP）, the structure and stability of two isomers -2-methoxymethyl-3-（3,4,5-trimethoxyphenyl） acrylic nitrile （ Ⅰ ） and 2- （3,4,5-trimethoxybenzyl） -3-methoxy acrylic nitrile （ Ⅱ ） have been studied theoretically with Gaussan03 by density functional theory （DPT） at the B3LYP/6-311G（ d, p） level. The conclusion has been obtained that the isomer II is more stable than isomer I in thermodynamics and chemical activity according to the analysis of molecular configuration, molecular total energy and energy gap. The conclusion is consistent with the experimental phenomena.