Phenol catechol and

Tao Y, A Fishman, WE Bentley, TK Wood (2004) Oxidation of benzene to phenol, catechol, and 1,2,3-trihydroxybenzene by toluene 4-monooxygenase of Pseudomonas mendocina KR 1 and toluene... 

Description of the model. Benzene and its metabolites (phenol, catechol, and hydroquinone) were assumed to compete for the same reaction site on the enzyme cytochrome P-450 2E1. In addition, phenol can undergo both oxidation and conjugation, although the enzymes for each of these reactions are localized in different compartments of the liver, and competition between them is thereby regulated. 

Grodnick JS, Dupre GD, Gulizia BJ, et al. 1983. Determination of benzene, phenol, catechol and hydroquinone in whole blood of rats and mice. J Chromatog Sci 21 289-292. 

Hattula, M.L., Wasenius, V.-M., Reunanen. H., and Arstila, A.U. Acute toxicity of some chlorinated phenols, catechols and cresols in trout, Bull. Environ. Contam. Toxicol, 26(3) 295-298, 1981. 

The pH values of efficient extraction correspond to the pH range where the molecular form of the respective phenol dominates. The recovery of 4-nitro-phenol, 2,4-dinitrophenol, 2,6-dinitrophenol, 4-chlorophenol, 1-naphthol, and 2-naphthol is above 90% (the ratio of aqueous organic phase volume is 3 1). The extraction of naphthol and 4-chlorophenol is significant even at pH > pffa, more than 40 and 24% at pH > 10, respectively. Recovery of picric acid (2,4,6-trinitrophenol) is about 90% at pH 1.5-12.0, where the anionic form of picric acid dominates. Obviously, the high extraction is caused by high hydrophobicity of picrate anions. Recovery of the phenol itself and diatomic phenols, catechol and resorcinol is rather moderate (79,58, and 20%, respectively pH 1-7), which could be explained by relatively high hydrophi-licity of these compounds. 

Catechol may be oxidized by peroxidases to the reactive intennediate benzo-1,2-quinone, which readily binds to proteins (Bhat et al., 1988) this process, catalysed by rat or human bone-marrow cells in the presence of H2O2 (0.1 mM), is stimulated by phenol (0.1-10 mM), and decreased by hydroquinone and by glutathione, which conjugates with benzo-l,2-quinone. These phenols (phenol, catechol and hydroquinone) may play a role in benzene toxicity to bone marrow all three are formed as benzene metabolites (Smith et al., 1989) and they interact in several ways as far as their bioactivation by (myelo)peroxidases is concerned (Smith et al., 1989 Subrahmanyam et al., 1990). 

Rasanen, L., Hattula, M.L. Arstila, A.U. (1977) The mutagenicity of MCPA and its soil metabolites, chlorinated phenols, catechols and some widely used slimicides in Finland. Bull, environ Contam. Toxicol., 18, 565-571... 

Hypertensin is soluble in alcohol, glacial acetic acid, phenol, and water, and insoluble in ether (61). Because it is inactivated by tyrosinase it probably contains a catechol or phenol group, and by amine oxidase, an amine group on an a-carbon atom (Figure 2). Hypertensin is inactivated by certain phenolic, catecholic, and amine oxidases, by pepsin, trypsin, chymotrypsin, and carboxypeptidase, and by hypertensinase found in plasma. The nature of hypertensinase is unknown, but it is probably not an oxidative enzyme. Because it is heat-labile, hypertensinase can be removed from blood and renin preparations by heating hypertensin itself is heat-stable. Lack of pure preparations of hypertensin has delayed its further chemical identification. 

Ferapontova EE, Castello J, Gorton L (2006) Bioelectrocatalytic properties of lignin peroxidase from Phanerochaete chrysosporium in reactions with phenols, catechols and lignin-model compounds. Biochim Biophys Acta 1760 1343-1354... 

The hydrogenation of phenols may proceed more readily than other aromatic compounds under proper use of catalyst and conditions. Over Ni-kieselguhr, hydroxyben-zenes such as phenol, catechol, and resorcinol are hydrogenated rapidly at 120-150°C under high pressure. Usually, the yields of the corresponding cyclohexanols are quantitative except for resorcinol, which gave only a 90% yield of cyclohexane-1,3-diol.70 An example is shown in eq. 11.11 for the hydrogenation of phenol. 

Benzene was also distributed to the kidney, lung, liver, brain, and spleen. The benzene metabolites phenol, catechol, and hydroquinone were detected in blood and bone marrow following 6 hours of exposure to benzene, with levels in bone marrow exceeding the respective levels in blood. The levels of phenol in blood and bone marrow decreased much more rapidly after exposure ceased than did those of catechol or hydroquinone, suggesting the possibility of accumulation of the latter two compounds. 

There are quantitative differences in the benzene metabolites produced by different species (Sabourin et al. 1988). Fischer 344 rats exposed to 50 ppm benzene had undetectable amounts of phenol, catechol, and hydroquinone in the liver, lungs, and blood. The major water-soluble metabolites were muconic acid, phenyl sulfate, prephenyl mercapturic acid, and an unknown The unknown was present in amounts equal to the amounts of phenyl sulfate in the liver phenyl sulfate and the unknown were the major metabolites in the liver. B6C3Fj mice exposed to 50 ppm benzene had detectable levels of phenol and hydroquinone in the liver, lungs, and blood catechol was detectable only in the liver and not in the lungs or blood. As in the rat, the unknown was present in amounts equal to the amounts of phenyl sulfate in the liver. Mice had... 

Dihydroxy phenols Catechols and 1,4-hydroquinones — Intramolecular hydrogen bonding revisited... 

A wide range of xenobiotics may undergo sulfation, principally those containing hydroxyl groups but also certain aromatic amines. Among the hydroxyllc substrates are alcohols, phenols, catechols and hydroxylamlnes (see Table IV). 

Coordination of O-Functional Ligands Derived from Phenolate, Catecholate and Enolate... 

The main processes for the manufacture of hydroxybenzaldehydes are based on the functionalisation of phenol, catechol and catechol derivatives (guaiacol, guetol,...). 

Dihydric Phenols (Catechols) and their Derivatives (i) 1,2-Dihydroxy Compounds... 

Chapter VII addresses the need to account for both physical and chemical phenomena, reaction and adsorption. In fact, consideration of these combined phenomena is, in the view of the authors, essential to provide effective kinetic and rate modeling for the photo conversion of organic and inorganic pollutants. Cases with several organic species are presented including methylene blue, phenol, chloro-phenol,di-chloro-phenol, catechol, and pyrogallol. 

Table 14.1 Mean percentage recoveries standard deviations of phenolic compounds in groundwater using different sorbents and working with on-line 10x2 mm ID stainless steel SPE pre-columns spiking, 4jig/L of each phenolic compound sample volume, 100 ml, except for phenol, catechol, and 2-amino-4-chlorophenol (50 mL), pH = 2.5...

The model reaction for hydroxylation is that of phenol. Catechol and hydroquinone are usually the main products for a maximum overall conversion of phenol not exceeding 20 %. 

---