Chlorinated 2-phenoxyphenols

Ryan JJ, Lizotte R, Newsome WH. 1984b. Study of chlorinated diphenyl ethers and chlorinated 2-phenoxyphenols as interferences in the determination of chlorinated dibenzo-p-dioxins and chlorinated dibenzofiirans in biological samples. J Chromatogr 303 351-360. 

Chlorinated dibenzo ip-dioxins are contaminants of phenol-based pesticides and may enter the environment where they are subject to the action of sunlight. Rate measurements showed that 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) is more rapidly photolyzed in methanol than octachlorodi-benzo-p-dioxin. Initially TCDD yields 2,3,7-trichlorodiben-zo-p-dioxin, and subsequent reductive dechlorination is accompanied by ring fission. Pure dibenzo-p-dioxin gave polymeric material and some 2,2 -dihydroxybiphenyl on irradiation. Riboflavin-sensitized photolysis of the potential precursors of dioxins, 2,4-dichlorophenol and 2,4,5-trichloro-phenol, in water gave no detectable dioxins. The products identified were chlorinated phenoxyphenols and dihydroxy-biphenyls. In contrast, aqueous alkaline solutions of purified pentachlorophenol gave traces of octachlorodibenzo-p-dioxin on irradiation. 

Hamilton, S.J., L. Cleveland, L.M. Smith, J.A. Lebo, andF.L. Mayer. 1985. Toxicity of pure pentachlorophenol and chlorinated phenoxyphenol impurities to fathead minnows. Environ. Toxicol. Chem. 5 543-552. 

Therefore, hplc methods seem more effective. By usiag a combiaed uv and electrochemical detection technique (52), the gem-chlotinated cyclohexadienones, the chlorophenols, and the phenoxyphenols present ia the chlorination mixtures can be determined with great accuracy. 

The reaction products from 2,4-dichlorophenol were tetrachloro-phenoxyphenols and tetrachlorodihydroxybiphenyls (Figure 5), as determined from their mass spectra and those of their methyl ethers. 4,6-Dichloro-2-(2, 4 -dichlorophenoxy)phenol (V) was the major phenoxy-phenol the mass spectral fragmentation pattern of o-hydroxyphenol ethers is quite characteristic since a hydrogen transfer occurs during the fragmentation (Figure 6). A trace of a trichlorophenoxyphenol also was detected and was formed presumably by the unsensitized reductive loss of chlorine, discussed previously. 

Commercial PCP preparations often contain variable amounts of chlorophenols, hexachloroben-zene, phenoxyphenols, dioxins, dibenzofurans, chlorinated diphenyl ethers, dihydroxybiphenyls, anisoles, catechols, and other chlorinated dibenzodioxin and dibenzofuran isomers. These contaminants contribute to the toxicity of PCP — sometimes significantly — although the full extent of their interactions with PCP and with each other in PCP formulations are unknown. Unless these contaminants are removed or sharply reduced in existing technical- and commercial-grade PCP formulations, efforts to establish sound PCP criteria for protection of natural resources may be hindered. 

Kitunen, V. H., Valo, R.J. Salkinoja-Salonen, M. S. (1985). Analysis of chlorinated phenols, phenoxyphenols and dibenzofurans around wood preserving facilities. International Journal of Environmental and Analytical Chemistry, 20, 13-20. 

As soon as they reach 70°C, phenols with low chlorine content (phenol, monochlorophenols, dichlorophenols) produce polychloro phenoxyphenols in the presence of polychlorinated gem-dichlorocyclohexadienones. In this case there is some consumption of polychlorinated gem-dichlorocyclohexadienones. 

Commercial PCP preparations often contain variable amounts of chlorophenols, hexachlorobenzene, phenoxyphenols, dioxins, dibenzofurans, chlorinated diphenyl ethers,... 

Rayne, S., Wan, R, Ikonomou, M. G., and Konstantinov, A. D., Photochemical mass balance of 2,3,7,8-TeCDD in aqueous solution under UV hght shows formation of chlorinated dihydroxybi-phenyls, phenoxyphenols and dechlorination products. Environ. Sci. Technol., 36,1995-2002,2002. 

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