Chlorodiphenyl ether PCDE

Polychlorinated diphenyl ethers (PCDEs) 10.1.4.1 2-Chlorodiphenyl ether (PCDE-1)... 

Polychlorinated diphenyl ethers (PCDE), also called bis(chlorophenyl) ethers and chlorodiphenyl oxides, are neutral aromatic compounds which resemble structurally polychlorinated biphenyls (PCB), except that one oxygen atom connects the phenyl rings. The empirical formula of the PCDEs is C12H10 nClnO, where n = 1-10. The structural formula of the PCDEs is given in Fig. 1. 

Technical chlorophenol formulations are the major sources of PCDEs in the environment [4,40,45,46]. Hydroxy chlorodiphenyl ethers (OH-PCDE), also called polychlorinated phenoxyphenols (PCPP), are the main impurities of chlorophenols [39,47,48]. 2-OH-PCDEs are called predioxins, since they are phenolic precursors to polychlorinated dibenzo-p-dioxins (PCDD) [47]. The levels of 2-hydroxy-nonaCDEs have varied between 0.6 mg kg-1 and 1100 mg kg-1 in commercial pentachlorophenol preparations (sodium salts) [47]. 3,4,5,6-tetrachloro-2-(2,3,4,5,6-pentachlorophenoxy)phenol) is the main impurity of commercial pentachlorophenols [48]. 

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