离子对烷基化法在2,4-D和2,4,5-T残留分析中的应用

有机阴离子可以和长碳链的季胺盐阳离子结合生成可溶于高介电常数有机溶剂的离子对.在此溶剂中,它可以和某些卤代烃发生复分解反应,生成季铵盐阳离子的卤化物及有机阴离子的相应烷基化物,故称离子对烷基化反应.此反应条件温和,转化率高,被广泛地应用于酸性及其它含活泼氢的有机化合物的烷基衍生物合成中.在这类有机物的分析中也得到应用.但尚未见应用于农药及其降解物残留分析中的报道. 2,4-D,2,4,5-T是典型的酸性有机农药,广泛用作农田除草剂.在二者的残留分析中,通常用CH_2N_2、BF_3CH_3OH、(CH_3)_2SO_4将它们烷基化,然后用气相色谱加以分析.近几年也有人用多卤素取代醇的BCl_3络合物或五氟苄基溴化物同Na_2CO_3作为

APPLICATION OF ION PAIR ALKYLATIONIN ANALYSIS OF 2, 4-D AND 2, 4, 5-T ATPESIDUAL LEVELS

Methyl esters of 2, 4-D and 2, 4, 5-T at residual levels were prepared by using ion pair alkylation and then analysed with ECD-GC.The effect of reaction conditions, including solvents, temperature, reaction time and amounts of reagents used, on yield were examined. High yield and good reproducibility were obtained. 2, 4-D and 2, 4, 5-T levels in 2, 4-D and 2, 4, 5-T fortified tap water and 2,4-D levels in 2,4-D containing canal water from wheat field were also determined.Compared with other conventional alkylation methods, the reaction is found to possess the advantage of requiring mild reaction conditions. Besides, the reagents used are more stable and less toxic, as well as in less amounts.