Transformation Kinetics and Mechanism of the Sulfonylurea Herbicides Pyrazosulfuron Ethyl and Halosulfuron Methyl in Aqueous Solutions
作者:Wei Zheng、Scott R. Yates、Sharon K. Papiernik
DOI:10.1021/jf800899e
日期:2008.8.1
herbicides, the hydrolysis rate was pH-dependent and increased with increasing temperature. The hydrolysis of both sulfonylureas was much faster in acidic or basic media than under neutral conditions. Identification of hydrolytic products by liquid chromatography-mass spectrometry (LC-MS) suggested that both PE and HM were subject to cleavage and contraction of the sulfonylurea bridge. The hydrolysis rate of
吡唑磺隆乙基(PE)和卤磺隆甲基(HM)是两种新型的高活性磺酰脲类除草剂,已广泛用于各种蔬菜和其他农作物的杂草控制。这两种除草剂具有相似的分子结构,仅在吡唑环上的取代不同。化学水解是影响磺酰脲类农药环境命运的主要过程。研究了PE和HM的水解转化动力学与pH和温度的关系。对于这两种除草剂,水解速率均取决于pH,并且随着温度的升高而增加。在酸性或碱性介质中,两种磺酰脲的水解都比在中性条件下快得多。通过液相色谱-质谱(LC-MS)鉴定水解产物表明,PE和HM均会受到磺酰脲桥的裂解和收缩。尽管在结构上相似,但在碱性溶液中,HM的水解速率明显高于PE。在碱性条件下,HM的吡唑环上的氯取代基使PE比PE对桥的收缩更敏感。HM和PE的水解相对不受环状寡糖(环糊精)的存在的影响,表明在水生环境中存在的天然含OH的有机化合物可能对这些磺酰脲类除草剂的转化影响很小。尽管在结构上相似,但在碱性溶液中,HM的水解