Pesticide Residue Laboratory, Department of Agricultural Chemicals, Bidhan Chandra Krishi Viswavidyalaya, Nadia, West Bengal, India.
J Environ Sci Health B. 2009 Nov;44(8):788-97. doi: 10.1080/03601230903238343.
The photolysis of a rice herbicide Bispyribac sodium (Sodium 2, 6-bis [(4, 6-dimethoxypyrimidin-2-yl) oxy] benzoate) has been studied in different aqueous medium (distilled water, pond water and Irrigation water) under the influence of UV (lambda max > or = 250 nm) and sunlight in presence or absence of sensitizers (TiO(2) and KNO(3)). The study was conducted under laboratory simulated condition which made it possible to evaluate the contribution of different factors viz. source of irradiation, solvent and sensitizers towards the photolysis of bispyribac sodium. The photodegradation proceeds via first order reaction Kinetics in all the cases. Five photo metabolites (M(1)-M(5)) were isolated in pure form by column chromatographic method from the irradiation system under UV influenced and TiO(2) as sensitizer. From the different spectral data (IR, NMR, UV-VIS, Mass) the structure of these five metabolites were assigned as M(1) (Phenol), M(2) [2, 6-Dihydroxy benzoic acid], M(3) [2, 6-bis [(4, 6 dimethoxypyrimidin-2yl) oxy] benzoic acid], M(4) [2-(3-Hydroxy-phenoxy)-pyrimidine-4, 6-diol] and M(5) as [2,4-Dihydroxy-3, 5-dimethoxy-6-(4-methoxy pyrimidine-2-yloxy)-benzoic acid]. Moreover, another six photometabolites (M(6)-M(11)) were identified from the different irradiation system on the basis of Micromass analysis. On the basis of MS/MS data analysis, the structure of these six photometabolites were assigned as M(6) [2-(4, 6-Dimethoxy-pyrimidin-2-yloxy)-6-hydroxy-benzoic acid], M(7) [2-Hydroxy-6-(4-hydroxy-6-methoxy-pyrimidin-2-yloxy)-benzoic acid], M(8) [4, 6-Dimethoxy-pyrimidin-2-ol], M(9) [6-Methoxy-pyrimidine-2, 4-diol], M(10) [2-Hydroxy-6-(pyrimidin-2-yloxy)-benzoic acid] and M(11) [2, 4, 6-Trimethoxy-pyrimidine]. The plausible Photodegradation pathways of bispyribac sodium in the present investigation were portrayed which proceeds via hydrolysis, hydrolytic cleavage, O-dealkylation, decarboxylation, dehydroxylation, O-alkylation and hydroxylation.
在不同的水介质（蒸馏水、池塘水和灌溉水）中，在紫外线（lambda max > or = 250nm）和阳光的影响下，研究了水稻除草剂双丙戊酸钠（Sodium 2,6-bis [(4,6-二甲氧基嘧啶-2-基)氧基] 苯甲酸）的光解。该研究是在实验室模拟条件下进行的，这使得评估不同因素（即辐射源、溶剂和敏化剂）对双丙戊酸钠光解的贡献成为可能。在所有情况下，光降解都通过一级反应动力学进行。通过柱色谱法从辐照体系中分离出五种纯形式的光代谢物（M(1)-M(5），其中一种在 UV 影响下和 TiO(2）作为敏化剂。根据不同的光谱数据（IR、NMR、UV-VIS、Mass），这些五种代谢物的结构被分配为 M(1)（苯酚）、M(2)[2,6-二羟基苯甲酸]、M(3)[2,6-双[(4,6-二甲氧基嘧啶-2-基)氧基]苯甲酸]、M(4)[2-(3-羟基苯氧基)-嘧啶-4,6-二醇]和 M(5）作为[2,4-二羟基-3,5-二甲氧基-6-(4-甲氧基嘧啶-2-基氧基）苯甲酸）。此外，根据微量分析，还从不同的辐照体系中鉴定出另外六种光代谢物（M(6)-M(11）。基于 MS/MS 数据分析，这些六种光代谢物的结构被分配为 M(6)[2-(4,6-二甲氧基嘧啶-2-基氧基）-6-羟基苯甲酸]、M(7)[2-羟基-6-(4-羟基-6-甲氧基嘧啶-2-基氧基）苯甲酸]、M(8)[4,6-二甲氧基嘧啶-2-醇]、M(9)[6-甲氧基嘧啶-2,4-二醇]、M(10)[2-羟基-6-(嘧啶-2-基氧基）苯甲酸]和 M(11)[2,4,6-三甲氧基嘧啶）。本研究描绘了双丙戊酸钠在水解、水解裂解、O-脱烷基化、脱羧、去羟化、O-烷基化和羟化等过程中的可能光降解途径。
