三种磺酰脲类除草剂水解反应机理的理论研究

Theoretical study on hydrolysis mechanism of three typical sulfonylurea herbicides

采用量子化学从头算方法在HF/6-31G(d)水平上对氯磺隆、甲嘧磺隆和氟嘧磺隆三种典型的磺酰脲类除草剂在酸性和中性条件下水解反应的机理进行理论研究,分别优化了各反应途径中反应物、过渡态、中间体以及产物的几何构型,并通过振动分析确定反应的过渡态和中间体的真实性。同时,在B3LYP/6-31G(d)水平上计算各驻点的单点能,以及溶剂效应对水解反应的影响。从能量上看,酸性条件更有利于水解反应的进行,与实验结果较为吻合.

The hydrolysis mechanisms of three typical sulfonylurea herbicides including chlorsulfuron, sulfometuron-methyl, primisulfuron-methyl in the acidic condition and the netural condition were studied by quantum chemistry of ab initio method at the level of HF/6 - 31G（d）. The geometric configurations of reactants, products,intermediates,and transition in the reactions were optimized and vibrational analyzed by performing the conformance of the transitions. Besides, the single-point energy was calculated and the influence of the solvent effect was discussed at the level of B3LYP/6 - 31G（d） too. That is to say, the hydrolysis reaction of three herbicides underwent more easily in the acidity than neutrality, which is essentially consistent with the experimental result.