4-Hydroxybiphenyl and 4,4 -dihydroxybiphenyl

Biological. Reported biodegradation products include 2,3-dihydro-2,3-dihydroxybiphenyl, 2,3-dihydroxybiphenyl, 2-hydroxy-6-oxo-6-phenylhexa-2,4-dienoate, 2-hydroxy-3-phenyl-6-oxohexa-2,4-dienoate, 2-oxopenta-4-enoate, phenylpyruvic acid (quoted, Verschueren, 1983), 2-hydroxy-biphenyl, 4-hydroxybiphenyl, and 4,4 -dihydroxybiphenyl (Smith and Rosazza, 1974). The microbe Candida lipolytica degraded biphenyl into the following products 2-, 3-, and 4-hydroxy-biphenyl, 4,4 -dihydroxybiphenyl, and 3-methoxy-4-hydroxybiphenyl (Cerniglia and Crow, 1981). 

A charge transfer complex is involved in the photochemical reaction between 4-cresol and tetranitromethane. Irradiation at 350 nm yields the o-nitrated product 235 ° . Other phenols such as phenol, 2- and 4-chlorophenol and 2- and 4-cresol behave in a similar manner and irradiation yields 2- and 4-nitrated products (236, 237) ° . The quantum yields for product formation are in the range 0.12-0.31. Only the formation of 3-nitrophenol from phenol is inhibited, as might be expected from attack at the 3-position, and shows a low quantum yield. It has been reported that 2-hydroxy- or 4-hydroxybiphenyl and 4,4 -dihydroxybiphenyl are the primary products formed from the photochemical reaction of biphenyl with sodium nitrate in aqueous methanol . Apparently the hydroxybiphenyls are prone to undergo photochemical nitration as a secondary process and yield the biphenyls 238 and 239 as well as 4,4 -dihydroxy-3,3 -dinitrobiphenyl, originally reported by Suzuki and coworkers under heterogeneous conditions. 

Biphenyl injected into the starfish Ophiocomina nigra was metabolized primarily to 2-hydroxybiphenyl, with smaller amounts of 4-hydroxybiphenyl and 4,4 -dihydroxybiphenyl being formed (Meyer and Bakke 1977). The percent of total metabolites were, respectively, 78, 14 and 8%. The parent compound was more evident in the seawater than in the tissues of the starfish, viz. seawater 45% biphenyl and 55% metabolites tissues 10% biphenyl and 90% metabolites, i.e. depuration of parent compound was faster than the rate of metabolism and/or depuration of metabolites. 

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