Direct and induced phototransformation of mecoprop [2-(4-chloro-2-methylphenoxy)propionic acid] in aqueous solution
Direct and induced phototransformation of mecoprop [2-(4-chloro-2-methylphenoxy)propionic acid] in aqueous solution
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DOI：
10.1002/1526-4998(200012)56:12
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发表时间：
2000-12
影响因子：
4.1
通讯作者：
L. Meunier;P. Boule
中科院分区：
文献类型：
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作者：
L. Meunier;P. Boule
在不同的pH、氧合和波长条件下，对Mecoprop进行辐照，研究其光转化反应。鉴定出4种主要的光产物：2-（4-羟基-2-甲基苯氧基）丙酸(I)、邻甲酚（II）、2-（5-氯-2-羟基-3-甲基苯基）丙酸（III）和4-氯-邻甲酚（IV）。在254 ~ 310 nm波段（UV-C或UV-B）照射时，I为主要光产物。在254 nm处，它的形成最初占转变的80%以上。这在以前的文献中没有报道。该反应是由异解光水解引起的。产品II只占转换的一小部分。化学计量学与分子形态不同：主要的光产物III是均裂后重排的产物。产物I、II和IV也作为次要光产物形成。还发现了其他一些次要的光产物。相比之下，在日光照射下或溶液在近紫外光（UV-A）下照射时，IV是主要的光产物。这种波长效应归因于诱导光转换的参与；高氯酸铁（III）或亚硝酸盐离子诱导光转化时，IV也是主要的光产物。在通常的环境条件下，分子形式的激发可以忽略不计，光转化主要是由于诱导的光反应。©2000化学工业协会
Mecoprop was irradiated under various conditions of pH, oxygenation and wavelengths in order to study the reactions involved in the phototransformation. Four main photoproducts were identified: 2-(4-hydroxy-2-methylphenoxy)propionic acid (I), o-cresol (II), 2-(5-chloro-2-hydroxy-3-methylphenyl)propionic acid (III) and 4-chloro-o-cresol (IV). When the anionic form of mecoprop was irradiated between 254 nm and 310 nm (UV-C or UV-B), I was the main photoproduct. At 254 nm its formation initially accounted for more than 80% of the transformation. It has not previously been reported in the literature. The reaction results from a heterolytic photohydrolysis. Product II accounted for only a low percentage of the transformation. The stoichiometry was different with the molecular form: the main photoproduct, III, resulted from a rearrangement after a homolytic scission. Products I, II and IV were also formed as minor photoproducts. Some other minor photoproducts were also identified. In contrast, IV was the main photoproduct under sunlight irradiation or when solutions were irradiated in near-UV light (UV-A). This wavelength effect is attributed to the involvement of an induced phototransformation; IV is also the main photoproduct when the phototransformation is induced by Fe(III) perchlorate or nitrite ions. In usual environmental conditions the excitation of the molecular form is negligible and the phototransformation is mainly due to induced photoreactions. © 2000 Society of Chemical Industry