Abstract
Biomimetic oxidation mediated by three types of iron porphyrins was examined for five organophosphrus pesticides, fenitrothion (I), cyanophos (II), tolclofos-methyl (III), butamifos (IV) and fenthion (V). The major products from I–IV were the corresponding phenols and each oxon formed via a phosphoxathiirane intermediate by oxidation at the P=S moiety similarly as reported for their mammalian metabolism by cytochrome P450 enzymes. Stepwise oxidation of the methylthio sulfur via sulfoxide to sulfone, and ester cleavage and oxidative desulfuration primarily proceeded for V. Both the electron distribution of the highest occupied molecular orbital and its energy level of the pesticides calculated by MNDO-PM3 were shown to control the reaction site and rate of oxidation at sulfur atoms. © Pesticide Science Society of Japan
