Phenol degradation dehydroxylation

It can be concluded from these observations that whereas benzoate produced by the carboxylation of phenols can be degraded, dehydroxylation with the formation of substituted benzoates may produce stable terminal metabolites. 

Glockler, R., A. Tschech, and G. Fuchs. 1989. Reductive dehydroxylation of 4-hydroxybenzoyl-CoA to benzoyl-CoA in a denitrifying, phenol-degrading Pseudomonas species. FEBS Letters 251 237-240. 

The anaerobic degradation of some hydroxybenzoates and phenols involves reductive removal of the phenolic hydroxyl group. The enzyme that dehydroxylates 4-hydroxybenzoyl-CoA in Thauera aromatica is a molybdenum-flavin-iron-sulfur protein (Breese and Fuchs 1998), and is similar to the enzyme from the nonsulfur phototroph Rhodopseudomonas palustris that carries out the same reaction (Gibson et al. 1997). 

It has become clear that benzoate occupies a central position in the anaerobic degradation of both phenols and alkylated arenes such as toluene and xylenes, and that carboxylation, hydroxylation, and reductive dehydroxylation are important reactions for phenols that are discussed in Part 4 of this chapter. The simplest examples include alkylated benzenes, products from the carboxylation of napthalene and phenanthrene (Zhang and Young 1997), the decarboxylation of o-, m-, and p-phthalate under denitrifying conditions (Nozawa and Maruyama 1988), and the metabolism of phenols and anilines by carboxylation. Further illustrative examples include the following ... 

The anaerobic degradation of phenol proceeds by carboxylation of phenyl phosphate, followed by dehydroxylation, and fission of the ring after partial reduction (Brackmann and Fuchs 1993). 

The degradation pathway of p-cresol in groundwater appears to proceed by oxidation of the methyl group to first give the corresponding benzaldehyde, then benzoic acid (Kuhn et al. 1988 Smolenski and Suflita 1987 Suflita et al. 1988, 1989). The hydroxybenzoic acid then can be either decarboxylated or dehydroxylated to phenol or benzoic acid, respectively. 

It seems clear that benzoate occupies a central position in the anaerobic degradation of both phenols and alkaryl hydrocarbons, and that carboxylation, hydroxylation, and reductive dehydroxylation are important—and less expected—reactions. 

Degradation, polyethylene Degradation, polymers, catalytic Dehydration, Cd-FAU Dehydration, clinoptilolite Dehydration, isopropanol Dehydration, K-LSX Dehydration, MOR Dehydrocyclodimerisation, butadiene Dehydrogenation, ethylbenzene Dehydrogenation, methanol Dehydroisomerisation, n-butane Dehydroxylation, phenol Delaminated zeolites De novo simulation DeNOx catalyst... 

Phenolic acid derivatives (cinnamic acids) and degradation products of flavonoids (phenylpropionic and phenylacetic acids) suffer transformations by caecal bacteria. The following transformations have been observed dehydroxylation of 3,4-dihydroxy derivatives to give 3-hydroxy compounds, demethylation of o-hydroxy-methoxyphenolic acids, reduction of the double bonds of cinnamic acids to yield the corresponding phenylpropionic acids, decarboxylation of cinnamic and phenylacetic acids (only when 4-hydroxyl is present), hydroxylation of... 

A biotechnological synthesis has also been demonstrated to be possible [58]. Thauera aromatica bacteria can use phenol as the only source of carbon under anaerobic conditions phenol is eventually converted into CO2 and water. The first step of the degradation path is the carboxylation of phenolphosphate to 4-hydroxybenzoic add which is then dehydroxylated to benzoic add [59] (Scheme 1.4). The carboxylation of phenol is carried out by a phenolcarboxylase enzyme, a new type of lyase [60]. The isolation of the enzyme from the cytoplasmic portion of the cell allows its use in vitro. In order to extend the lifetime of the enzyme, its supported form on low melting agar can be used [61]. Cut-off membranes (that allow the passage of macromolecules of a given size) [58] can be... 

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