Cresol degradation

Cresols degrade rapidly in air. Removal during the day is dominated by the reaction with hydroxyl radical (HO-), while nighttime removal is probably dominated by the nitrate radical. Reaction with other oxidants in air (e.g., ozone) will be much slower than reactions with hydroxyl or nitrate radical (Atkinson and Carter 1984). 

Cresols degrade rapidly in the environment (see Section 5.3.2). The degradation products are also removed rapidly. The products resulting from the degradation of the three isomers of cresol in the environment are not unique to these compounds. 

HPLC systems were helpful in monitoring cephalosporin production [174] and p-cresol degradation [392]. Other HPLC systems have been reported to serve for the control of penicillin production, namely via the precursor feed [62, 288],3-chlorobenzoate conversion [375] or naphthalenesulfonic acid reduction [279], as well as amino acids [444,445]. HPLC is also found to be useful when linked to biochemical assays [316]. Mailinger et al. [262] have discussed many important aspects of on-line HPLC systems. 

Pelizetti et al. detailed the photocatalytic mineralisation of ortho-, para-and mefa-cresols [116]. As with chlorophenol, methyl catechol and hydro-quinone were detected as major by-products. The o- and p-crcsols were observed to degrade with first order kinetics while the m-cresol degradation followed zero order kinetics at pH 3. Under 3 h photocatalysis time in alkaline conditions m-cresol kinetics become first order which was proposed to be due to lower surface coverage of the cresol at this pH due to electrostatic repulsion with the titania surface. In air saturated solutions the time for mineralisation was around 8 h. The mineralisation time was, however, reduced to 2.5 h in suspensions sparged with oxygen. 

Methylphenol is converted to 6-/ f2 -butyl-2-methylphenol [2219-82-1] by alkylation with isobutylene under aluminum catalysis. A number of phenoHc anti-oxidants used to stabilize mbber and plastics against thermal oxidative degradation are based on this compound. The condensation of 6-/ f2 -butyl-2-methylphenol with formaldehyde yields 4,4 -methylenebis(2-methyl-6-/ f2 butylphenol) [96-65-17, reaction with sulfur dichloride yields 4,4 -thiobis(2-methyl-6-/ f2 butylphenol) [96-66-2] and reaction with methyl acrylate under base catalysis yields the corresponding hydrocinnamate. Transesterification of the hydrocinnamate with triethylene glycol yields triethylene glycol-bis[3-(3-/ f2 -butyl-5-methyl-4-hydroxyphenyl)propionate] [36443-68-2] (39). 2-Methylphenol is also a component of cresyHc acids, blends of phenol, cresols, and xylenols. CresyHc acids are used as solvents in a number of coating appHcations (see Table 3). 

Methylene chloride is one of the more stable of the chlorinated hydrocarbon solvents. Its initial thermal degradation temperature is 120°C in dry air (1). This temperature decreases as the moisture content increases. The reaction produces mainly HCl with trace amounts of phosgene. Decomposition under these conditions can be inhibited by the addition of small quantities (0.0001—1.0%) of phenoHc compounds, eg, phenol, hydroquinone, -cresol, resorcinol, thymol, and 1-naphthol (2). Stabilization may also be effected by the addition of small amounts of amines (3) or a mixture of nitromethane and 1,4-dioxane. The latter diminishes attack on aluminum and inhibits kon-catalyzed reactions of methylene chloride (4). The addition of small amounts of epoxides can also inhibit aluminum reactions catalyzed by iron (5). On prolonged contact with water, methylene chloride hydrolyzes very slowly, forming HCl as the primary product. On prolonged heating with water in a sealed vessel at 140—170°C, methylene chloride yields formaldehyde and hydrochloric acid as shown by the following equation (6). 

Phenoxaphosphine ring-containing poly (1,3,4-oxa-diazoles) were synthesized by cyclodehydration of poly-hydrazides obtained from (BCPO) and aliphatic and aromatic dihydrazines [152]. All these polymers are soluble in formic acid, w-cresol and concentrated H2SO4. The polyhydrazides yield transparent and flexible films when cast from DMSO solution under reduced pressure at 80-100°C. The polyhydrazides exhibit reduced viscosities of 0.24-0.40 dl/g in DMAC. Phenoxaphosphine ring-containing oxadiazole polymers showed little degradation below 400°C. 

Novolac network degradation mechanisms vary from tiiose of resole networks due to differences in crosslinking metiiods. Nitrogen-containing linkages must also be considered when HMTA (or other crosslinking agent) was used to cure novolac networks. For example, tribenzylamines, formed in HMTA-cured novolac networks, decompose to cresols and azomethines (Fig. 7.50). 

Rudolph A, A Tschech, G Euchs G (1991) Anaerobic degradation of cresols by denitrifying bacteria. Arch Microbiol 155 238-248. 

Bonting CFC, S Schneider, G Schmidtberg, G Fuchs (1995) Anaerobic degradation of m-cresol via methyl oxidation to 3-hydroxybenzoate by a denitrifying bacterium. Arch Microbiol 164 63-69. 

Hopper DJ, PJ Chapman (1971) Gentisic acid and its 3- and 4-methyl-substituted homologues as intermediates in the bacterial degradation of ra-cresol, 3,5-xylenol and 2,4-xylenol. Biochem J 122 19-28. 

Londry KL, PM Fedorak, JM Suflita (1997) Anaerobic degradation of m-cresol by a sulfate-reducing bacterium. Appl Environ Microbiol 63 3170-3175. 

Muller JA, AS Galuschko, A Kappler, B Schink (2001) Initiation of anaerobic degradation of / -cresol by formation of 4-hydroxybenzylsuccinate in Desulfitobacterium cetonicum. J Bacteriol 183 752-757. 

Ramanand K, JM Suflita (1991) Anaerobic degradation of m-cresol in anoxic aquifer slurries carboxylation reactions in a sulfate-reducing bacterial enrichment. Appl. Environ. Microbiol. 57 1689-1695. 

Enrichment factors during the anaerobic degradation of o-xylene, m-xylene, m-cresol, and p-cresol by pure cultures of sulfate-reducing bacteria that use the fumarate pathway ranged from -1.5 to -3.9 ppm (Morasch et al. 2004). It was therefore proposed that this could be applied to evaluating in situ bioremediation of contaminants that use this pathway for biodegradation. 

Perron N, Welander U (2004) Degradation of phenol and cresols at low temperatures using a suspended-carrier biofilm process. Chemosphere 55 45-50... 

CASRN 94-74-6 molecular formula CgffgClOs FW 200.63 Biological. Cell-free extracts isolated from Pseudomonas sp. in a basal salt medium degraded MCPA to 4-chloro-o cresol and glyoxylic acid (Gamar and Gaunt, 1971). 

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