Pentachlorophenol dehalogenation

Schenk T, R Muller, F Lingens (1990) Mechanism of enzymatic dehalogenation of pentachlorophenol by Arthrobacter sp. strain ATCC 33790. J Bacterial 172 7272-7274. 

Xun L, E Topp, CS Orser (1992a) Confirmation of oxidative dehalogenation of pentachlorophenol by a Flavobacterium pentachlorophenol hydroxylase. J Bacterial 174 5745-5747. 

Electrochemical dehalogenation (applicable to pentachlorophenol, trichlorobenzene, hexachlorobenzene, etc.)... 

Oxidative dehalogenation of aromatic halogens should not occur because there is no hydrogen atom on the carbon involved however, it often does occur. One mechanism likely involves ipso addition as will be discussed later and as proposed for the dechlorination of pentachlorophenol (Fig. 4.65) (131). 

Soil Under anaerobic conditions, pentachlorophenol may undergo sequential dehalogenation to produce /n-chlorophenol, tetra-, tri-, and dichlorophenols (Kobayashi and Rittman, 1982). In aerobic and anaerobic soils, pentachloroanisole was the major metabolite, with minor quantities of... 

Halophenols are readily hydrogenated to give cyclohexanols by use of Raney Ni-A1 alloy in a saturated barium hydroxide solution under mild conditions.78 For example, when Raney Ni-Al alloy (12 g) was added slowly to a mixture of pentachlorophenol (1.73 g, 6.5 mmol) and a saturated aqueous solution of Ba(OH)2 at 60°C, cyclohexanol was obtained in 91 % yield. It has been suggested that halophenols are first hydrogenated to halocyclohexanols and then dehalogenated to give cyclohexanols, since phenol itself gave only a trace amount of cyclohexanol with an almost quantitative recovery of phenol under these conditions. 

The decomposition of pinacyanol chloride dye using octahedral layered mixed-valent manganese oxides has been published [81]. Catalytic reduction reactions using birnessite have been tried for removing pentachlorophenol (PCP) from soil and water (detoxyfication) [82]. Transformation and dechlorination of PCP incubated with peroxidase, laccase, or birnessite is decreased in the presence of humic monomers as cosubstrate. The dehalogenation number for birnessite is 3.3, compared with 3.5 for peroxidase and 1.5 for laccase [82]. 

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