The phenylpyrazole insecticide fipronil (I) photolyzes to its desthio product (II) in aqueous solution. However, the necessity of an intervening oxidation to a sulfone intermediate (III) has not been resolved, and the photodegradation products of II have not been identified. Using GC-MS, HPLC-UV/vis, electrospray MS, (19)F NMR, and GC-TSD, our objective was to characterize the photodegradation pathways of I, which would clarify the role of III, identify products of II, and explain unbalanced mass accounts in previous studies. Findings showed that II is formed directly and photochemically from I, confirmed by the greater stability of III (t(1/2) 112 h), and that successive oxidations of I to III and then a sulfonate (IV) comprise a second pathway. Compound II underwent photodechlorination, substitution of chlorine by trifluoromethyl, and pyrazole ring cleavage. This work is significant to understanding the photochemistry of novel phenylpyrazole pesticides in the environment.

中文翻译：

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阐明氟虫腈的光降解途径。

苯基吡唑杀虫剂氟虫腈（Ⅰ）在水溶液中光解成其脱硫产物（Ⅱ）。然而，尚未解决对砜中间体（III）进行中间氧化的必要性，并且尚未鉴定II的光降解产物。使用GC-MS，HPLC-UV / vis，电喷雾MS，（19）F NMR和GC-TSD，我们的目标是表征I的光降解途径，从而阐明III的作用，鉴定II的产物和在以前的研究中解释不平衡的海量账户。研究结果表明，II是由I直接形成并由光化学形成的，这由III的更大稳定性（t（1/2）112 h）所证实，并且I至III的连续氧化以及随后的磺酸盐（IV）构成了第二条途径。对化合物II进行光脱氯，用三氟甲基取代氯，和吡唑环裂解。这项工作对于理解环境中新型苯基吡唑类农药的光化学具有重要意义。