Mazellier Patrick, Busset Cécile, Delmont Anne, De Laat Joseph
Laboratoire de Chimie de l'Eau et de l'Environnement, UMR CNRS 6008, Université de Poitiers ESIP, 40 Avenue du Recteur Pineau, Poitiers Cedex, France.
Water Res. 2007 Dec;41(20):4585-94. doi: 10.1016/j.watres.2007.06.066. Epub 2007 Jul 12.
A comparative study of the transformation of the herbicide fenuron (1,1-dimethyl-3-phenylurea) by hydroxyl radicals and carbonate radicals in aqueous solution (pH 7.2-phosphate buffer) has been undertaken. Hydroxyl radical was generated by the well-known photolysis of hydrogen peroxide at 254 nm and carbonate radical was formed by photolysis of Co(NH(3))(5)CO(3)(+) at 254 nm. Competitive kinetic experiments were performed with atrazine used as the main competitor for both processes. Accordingly, the second-order rate constant of reaction between fenuron and carbonate radical was found to be (7-12+/-3)x10(6)M(-1)s(-1) [(7+/-1)x10(9)M(-1)s(-1) for hydroxyl radical]. The formation of degradation products was studied by LC-MS in the two cases and a comparison has been performed. The reaction with carbonate radical leads to the formation of a quinone-imine derivative which appears as the major primary product together with ortho and para hydroxylated compounds. These two compounds represent the major products in the reaction with hydroxyl radicals. The reaction of both radicals also leads to the transformation of the dimethylurea moiety.
开展了一项关于除草剂非草隆（1,1 - 二甲基 - 3 - 苯基脲）在水溶液（pH 7.2 - 磷酸盐缓冲液）中被羟基自由基和碳酸根自由基转化的对比研究。羟基自由基通过在254 nm波长下过氧化氢的著名光解反应产生，碳酸根自由基通过在254 nm波长下Co(NH₃)₅CO₃⁺的光解反应形成。使用莠去津作为这两个过程的主要竞争剂进行了竞争动力学实验。据此，发现非草隆与碳酸根自由基反应的二级速率常数为(7 - 12 ± 3)×10⁶ M⁻¹ s⁻¹ [羟基自由基为(7 ± 1)×10⁹ M⁻¹ s⁻¹]。在这两种情况下通过液相色谱 - 质谱联用研究了降解产物的形成并进行了比较。与碳酸根自由基的反应导致形成一种醌 - 亚胺衍生物，它与邻位和对位羟基化化合物一起作为主要初级产物出现。这两种化合物是与羟基自由基反应中的主要产物。两种自由基的反应还导致二甲基脲部分的转化。
