Iron-Porphyrin catalyzed oxidation of permethrin and fenvalerate

Abstract

Biomimetic oxidation of a trans isomer of permethrin, fenvalerate, together with the corresponding chrysanthemic acid and alcohol moieties was conducted using catalytic amounts of six iron-porphyrins having different substituents, not only at b-and meso-positions but also the axial ligand of iron in the presence of hydrogen peroxide or meta-chloroperbenzoic acid as an oxidant. The several degradation products via cleavage of ester and ether linkages and hydroxylation were identified and some were found to be in vivo metabolites previously reported in plants, animal and insects. The introduction of electron-withdrawing substituents at b-and mesopositions of a porphyrin ring resulted in higher conversion and the weak electron donor as the axial ligand of iron was found to increase the oxidative reactivity of porphyrin. ©Pesticide Science Society of Japan Keywords: biomimetic oxidation, fenvalerate, iron-porphyrin, permethrin. Materials and Methods Chemicals. trans-Permethrinand their potential degradates were synthesized in our laboratory by the reported methods.9-13) 14 C-I and II were prepared in our laboratory according to the reported procedures 14,15) and their radio-chemical purities were determined to be greater than 98% by HPLC. The specific activity of 14 C-I labeled at 1-position of the cyclopropyl ring and those of 14 C-II uniformly labeled at chlorophenyl and phenoxyphenyl rings were 5.06, 11.2 and 10.5 MBq mg Ϫ1 , respectively. The 14 C-derivatives corresponding to the alcohol moieties, PBalc and PBacid as well as the chrysanthemic acid derivatives of I were prepared during the synthesis of 14 C-I and II. 14 C-labeled CRA was also synthesized by the reported method.16) Abbreviations and the structure of reference standards employed in this study are presented in Table I. Other than the above reference standards, mono-hydroxylated compounds 9,17) of I, II, PBalc, PBacid and t-Cl 2 CA, oxidized compounds at the alkenyl methyl group of CRA 18) , carboxy and amide derivatives of II and dePh-II 13) , 2,3-dihydroxybenzoic acid, 3,5-dihydroxybenzoic acid and phenoxymandelic acid were used for HPLC and TLC analyses, but were not detected and are not listed in Table 1. The six iron porphyrins (Fig. 2) having different substituents at b-and meso-positions of the ring and an axial ligand were used. F 20 TPPFeCl and 4OMeTPPFeCl from Sigma-Aldrich Japan Co., Ltd. (Tokyo, Japan), F 20 Br 8 TPPFeCl from Wako Pure Chemical Industries, Ltd. (Osaka, Japan), and F 20 Br 8 -TPPFeNO 3 and F 20 Br 8 TPPFeCF 3 SO 3 from Funakoshi Co., Ltd. (Tokyo, Japan) were respectively purchased and used without further purification. Cl 8 TPPFeCl was synthesized in our laboratory as reported.19) The apparent valence of iron atom is ϩ3 in all porphyrins. Hydrogen peroxide (H 2 O 2 ) and meta-chloroperbenzoic acid (mCPBA) were purchased from Wako (Japan) and Sigma-Aldrich Japan Co., Ltd. (Tokyo, Japan), respectively, and other reagents were of the purest grade (99%) from Nacalai Tesque, Inc. (Kyoto, Japan). Biomimetic OxidationEach radio...

Photodegradation of Strobilurin Fungicide Mandestrobin in Water

“…(6 RS )- N ,1,4-Trimethyl-6,11-dihydrodibenzo­[ b , e ]­oxepine-6-carboxamide, 4 , was prepared by treating 3 with p -toluenesulfonic acid monohydrate in heated xylene . (2 RS )-2-(2-Hydroxymethylphenyl)-2-methoxy- N -methylacetamide, 5 , was prepared by treating 1 with 5,10,15,20-tetrakis­(pentafluorophenyl)-21 H , 23 H -porphyrin iron­(III) chloride, and m -perchlorobenzoic acid . Their chemical structures were confirmed by LC-MS and 1 H NMR analyses.…”

Theoretical and organic chemical approaches to environmental behavior and metabolism of pesticides

“…10). 31,53) Fenvalerate underwent not only the cleavage of ester and ether linkages and hydration of the cyano group but also oxidation at the terminal phenyl ring at 2′ and 4′ positions to form 4′-OH and quinone (Q) derivatives, 53) as shown in Fig. 11, most of which were reported in plant and soil metabolism studies.…”

“…21) The catalytic oxidation by P450 proceeds via the stepwise incorporation of two electrons and O 2 to finally form the oxo-iron (IV) porphyrin π-cation radical (OPCR), which transfers oxygen to a substrate molecule. 53) This reactive intermediate is known to be artificially produced via the so-called shunt pathway by the reaction with a peroxide. As a P450 model, we used several syn-thetic iron porphyrins with enough redox potential to oxidize a pesticide molecule (Fig.…”

“…11, most of which were reported in plant and soil metabolism studies. In order to theoretically investigate the oxidation mechanism, we conducted MNDO-PM3 MO calculations to obtain the energy levels of several occupied MOs of esfenvalerate (2S, αS isomer), 53) and that of the dπ-pπ MO (E dπ-pπ ) localized at each O-Fe IV -Cl moiety of three OPCRs assuming the spin state of S=3/2 (quartet). 54) Incidentally, the perturbation theory qualitatively implies that the reaction proceeds efficiently between two sites where the energy levels of interacting MOs with high electron densities are close to each other.…”

“…11 means the possible formation of 4′-OH, Q and desphenyl derivatives by the reaction with the OPCRs of Cl 8 TPPFeCl and F 20 TPPFeCl but not by that of F 20 Br 8 TPPFeCl, which is in good agreement with the experimental results. 53) Furthermore, we conducted oxidation of the insect growth regulator [ 14 C] pyriproxyfen by using F 20 TPPFeCl and H 2 O 2 in paral- Dissipation half-life in a day. b) Dissolved organic carbon in mg carbon L −1 .…”