有机磷农药敌百虫的水解特性和水解机理研究

Hydrolysis Characteristics and Mechanism of Organophosphorus Pesticide Trichlorfon

本文为了评价广谱有机磷农药在水环境中的自发降解规律及其安全性,以杀虫剂敌百虫(Trichlorfon,TCF)为对象,通过室内模拟实验,研究了其在不同pH及温度下的自发水解特性,应用^(31)P核磁共振(^(31)P-NMR)技术与气相色谱-质谱联用(GC-MS)技术对其水解产物进行了鉴定。结果表明,敌百虫在不同pH条件下水解速度差异明显,在酸性条件下比较稳定,pH=5时几乎不自发水解,pH=6时水解缓慢;在中性及碱性(pH=7~9)条件下不稳定,水解速度随着pH升高而加快;温度显著影响敌百虫的水解过程,水解速度随着温度的升高而加快,温度效应系数Q为2.11~4.63。敌百虫的自发水解产物主要有敌敌畏、亚磷酸二甲酯、水合氯醛、三氯乙醛,据此推断敌百虫水解路径有重排反应、亲核取代反应2种,其中重排反应是主要水解路径。敌百虫自发水解过程受pH、温度影响显著,水解产生毒性更强的敌敌畏,研究结果可为敌百虫在农业活动中的科学使用、敌百虫污染治理提供科学依据。

To evaluate the spontaneous degradation rule and safety of broad-spectrum organophosphorus pesticides in aqueous environment,the spontaneous hydrolysis characteristics of trichlorfon(TCF)at various pH and temperature were analyzed through indoor simulation experiments,and its hydrolysates were identified using^(31)P nuclear magnetic resonance(^(31)P-NMR)and gas chromatography-mass spectrometry(GC-MS).The results showed that the hydrolysis rate of trichlorfon varied markedly under different pH conditions,and it was relatively stable under acidic conditions.It hardly hydrolyzed at pH=5,and it slowly hydrolyzed at pH=6.However,it was unstable under neutral and alkaline conditions(pH=7~9),and the hydrolysis rate raised with the increase of pH.Temperature significantly affected the hydrolysis process of trichlorfon.The hydrolysis rate increased when temperature rising,and the temperature effect coefficient Q was 2.11~4.63.The spontaneous hydrolysis products of trichlorfon were mainly dichlorvos,dimethyl phosphite,chloral hydrate and chloral.From this,it was deduced that there were two hydrolysis paths for trichlorfon:nucleophilic substitution reaction and rearrangement reaction,with rearrangement reaction serving as the primary hydrolysis pathway.The trichlorfon’s spontaneous hydrolysis process,which resulted in the production of more dangerous dichlorvos,was significantly influenced by temperature and pH.The results can provide a scientific basis for the rational use of trichlorfon in agricultural activities and the control of trichlorfon pollution.