Division of Agricultural Chemicals, Indian Agricultural Research Institute, New Delhi -110012, India.
J Environ Sci Health B. 2009 Jun;44(5):435-41. doi: 10.1080/03601230902934785.
The degradation of thiamethoxam [(EZ)-3-(2-chloro-1,3-thiazol-5-yl-methyl)-5-methyl-1,3,5-oxadiazinan-4-ylidene (nitro) amine] insecticide in buffers at different pH and temperature levels was investigated in laboratory studies. Acidic hydrolysis under conventional heating conditions and alkaline hydrolysis under both conventional heating and microwave conditions were carried out. Different hydrolysis products were found to form under alkaline and acidic conditions. Hydrolysis of thiamethoxam in acidic, neutral and alkaline buffers followed first-order reaction rate kinetics at pH 4, 7 and 9.2, respectively. Thiamethoxam readily hydrolyzed in alkaline buffer but was comparatively stable in neutral buffer solution. The main products formed under different conditions were characterized on the basis of infrared (IR), (1)H-NMR and Mass spectroscopy. The possible mechanisms for the formation of these hydrolysis products have also been proposed.
在实验室研究中，考察了噻虫嗪[(EZ)-3-(2-氯-1,3-噻唑-5-基甲基)-5-甲基-1,3,5-恶二嗪烷-4-亚基(硝基)胺]杀虫剂在不同 pH 值和温度水平的缓冲液中的降解情况。在常规加热条件下进行酸性水解，在常规加热和微波条件下进行碱性水解。在碱性和酸性条件下发现形成了不同的水解产物。在 pH 值为 4、7 和 9.2 的酸性、中性和碱性缓冲液中，噻虫嗪的水解分别遵循一级反应动力学。噻虫嗪在碱性缓冲液中容易水解，但在中性缓冲溶液中相对稳定。根据红外（IR）、（1）H-NMR 和质谱对不同条件下形成的主要产物进行了表征。还提出了这些水解产物形成的可能机制。
