Identification of CNP, Chlomethoxynil and TCNP in Corbicula

Studies on Residual Diphenyl Ether Herbicides in Foods. I

Abstract

Three unknown peaks were found on ECD gaschromatograms of n-hexane extracts from corbicula, appearing closely after organochlorine pesticides.
These three substances were purified by silver nitrate-coated florisil column chromatography and high performance liquid chromatography. Two of them were identified as CNP (2, 4, 6-trichrophenyl-4′-nitrophenyl ether) and chlomethoxynil (2, 4-dichlorophenyl-3′-methoxy 4′-nitrophenyl ether) which are widely used as rice paddy herbicides in Japan.
The other constituent was suspected from its mass spectrum to be a diphenyl ether derivative with four chlorine atoms and a nitro group. Later, it was identified as a TCNP (2, 3, 4, 6-tetrachlorophenyl-4′-nitrophenyl ether), as a result of two synthetic reactions; 1) chlorination of CNP and 2) a coupling reaction on 2, 3, 4, 6-tetrachlorophenol and 1-fluoro-4-nitrobenzene.
TCNP is present in commercial CNP herbicide, and is presumably a byproduct of CNP synthesis.