Photochemistry of parathion in the plant cuticle environment: Model reactions in the presence of 2‐propanol and methyl 12‐hydroxystearate

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Abstract
On UV‐irradiation (λ > 280 nm), photodegradation of parathion dissolved in 2‐propanol took place mainly by reduction of the phenylnitro group. The photoreduction intermediates so formed then combined, yielding primarily azoxyparathion which, upon further irradiation, rearranged into 2‐hydroxyazoparathion.When parathion was irradiated in the presence of the cutin acid 12‐hydroxystearic acid (as the methyl ester), azoparathion, azoxyparathion and 2‐hydroxyazoparathion were the dominant photoproducts if the reaction was performed in thin‐layer films of the 12‐hydroxystearate. Irradiation of parathion dissolved in a solution of the 12‐hydroxystearate in cyclohexane yielded mainly paraoxon.Furthermore, in all experiments, photolysis of the P—O ester bonds of the parent compound as well as of the photoproducts was observed at low levels.