P-Cresol, oxidation

Orenes-Pinero E, Garcia-Carmona F and Sanchez-Ferrer A. 2005. A kinetic study of p-cresol oxidation by quince fruit polyphenol oxidase. J Agric Food Chem 53(4) 1196-1200. 

Ryu. K.. D.R. Stafford, and J.S. Dordick Peroxidase-Catalyzed Polymerization of Phenols Kinetics of p-Cresol Oxidation in Organic Media, in Biocatalysis in Agncultural Biotechnology, J.R. Whitake, ed. ACS Symp. Ser. No. 389. 

In order to more fully understand the effect of dioxane on peroxidase catalysis, we evaluated the kinetics of p-cresol oxidation in aqueous buffer — 0.25 p.g/mL peroxidase solutions dissolved in 5 mL aqueous buffer, pH 7, containing from 0.25-9.5 mM p-cresol and 0.25 mM H2O2... 

Whited GM, DT Gibson (1991b) Toluene-4-monooxygenase, a three-component enzyme system that catalyzes the oxidation of toluene to p-cresol in Pseudomonas mendocina KRl. J Bacteriol 173 3010-3016. 

Applications Van der Maeden et al. [646] first used GE-HPLC for the qualitative and quantitative analysis of oligomeric mixtures, such as low-MW resins (epoxy up to 16-mer, o-cresol novolak up to 16-mer, p-cresol novolak up to 13-mer), prepolymers (poly-(2,6-diphenyl-p-phenylene oxide) up to 20-mer), PET (up to 14-mer) and ethoxylated octaphenol surfactants (up to 19-mer). In many GE-HPLC separations of oligomeric mixtures, a compromise has to be found between sample loading, injection volume and compatibility of the sample solvent and the initial phase system. Therefore,... 

Diazo aminobenzene Di-t-butyl-p-cresol Dibutyl tin maleate Dibutyl tin oxide Dichlorophene 2,4-Dichiorophenoxy ethyl benzoate... 

Tetrahydrofuran has been reported to exhibit an absorption maximum at 280 nm (52,56), but several workers have shown that this band is not produced by the purified solvent (30,41,57). Oxidation products from THF have been invoked in order to account for the appearance of the 280-nm band in PVC films that are solvent-cast from THF in air (57. 581. However, in some reported cases (56,59), this band was undoubtedly produced, at least in part, by a phenolic antioxidant (2.6-di-tert-butyl-p-cresol)(59) in the solvent. Since certain -alkylphenols have now been shown to be powerful photosensitizers for the dehydrochlorination of PVC (60), it is clear that antioxidant photosensitization might well have been responsible for some of the effects attributed previously (56) to THF alone. On the other hand, enhanced rates of photodegradation under air have also been observed for PVC films cast from purified THF (57), a result which has been ascribed to radical formation during the photooxidation of residual solvent (57,61). Rabek et al. (61) have shown that this photooxidation produces a-HOO-THF, a-HO-THF, and y-butyro-lactone, and they have found that the hydroperoxide product is an effective sensitizer for the photodehydrochlorination of PVC at X = 254 nm (61). 

Inhibited oxidation of RH occurs through a relatively large number of reactions (see Chapter 4), but the primary mechanism of inhibited oxidation is determined by a few key reactions. For example, cumene is oxidized in the presence of p-cresol at 320-380 K... 

Fig. 12. Electroenzymatic oxidation of p-cresol under catalysis by PCMH in. long-time batch electrolysis under formation of p-hydroxy benzylalcohol (alcohol) and p-b. .roxy benzaldehyde (aldehyde) (PCMH 16 U = 5.6 nmol PEG-20000 ferrocene 3 0.51 mmr - 9.45 pmol ferrocene starting concentration of p-cresol 41.25 mM = 0.66 mmol additions o. substrate after 4140 min (0,0925 mmol), 5590 min (0.0784 mmol), 6630 min (0.184 mmol), 11253 min (0.371 mmol), in 10 ml tris/HCl-buffer of pH 7.6 divided cell Sigraflex-anode 26 cm2)...

Pure cultures of a Fe(III) reducing bacterium have been shown to obtain energy for growth by oxidizing benzoate, toluene, phenol or p-cresol with Fe(III) as the sole electron acceptor (Lovely et al., 1989, 1991). Such redox reactions are important because, at the onset of anaerobic conditions, e.g., in sediments and subsurface environments, Fe(III) oxides are the most abundant oxidants. 

A quite different limonene conversion is the dehydrogenation into p-cymene, thus giving a green aromatic. Pd-catalysts give yields of >95% [18]. p-Cymene can be oxidized to the hydroperoxide, which can be rearranged to p-cresol, a valuable chemical. 

Lovley DR, Lonergan DJ. 1990. Anaerobic oxidation of tolnene, phenol, and p-cresol by the dissimilatory iron-reducing organisms, GS-15. Appl Environ Microbiol 56 1858-64. 

Phenols (p-cresol, guaiacol, pyrogallol, catechol) and aromatic amines (aniline, p-tolidine, o-phenyldiamine, o-dianisidine) are typical substrates for peroxidases [90 -109]. These compounds are oxidized by hydrogen peroxide or hydroperoxides under peroxidase catalysis to generate radicals, which after diffusion from the active center of the enzyme react with further aromatic substrates to form dimeric, oligomeric or polymeric products. 

Chemical/Physical. Products identified from the reaction of toluene with nitric oxide and OH radicals include benzaldehyde, benzyl alcohol, 3-nitrotoluene, p-methylbenzoquinone, and o, m, and p-cresol (Kenley et ah, 1978). Gaseous toluene reacted with nitrate radicals in purified air forming the following products benzaldehyde, benzyl alcohol, benzyl nitrate, and 2-, 3-, and 4-nitro-toluene (Chiodini et al., 1993). Under atmospheric conditions, the gas-phase reaction with OH radicals and nitrogen oxides resulted in the formation of benzaldehyde, benzyl nitrate, 3-nitrotoluene, and o-, m-, and p-cresol (Finlayson-Pitts and Pitts, 1986 Atkinson, 1990). 

A method was proposed for the preparation of p-hydroxybenzoic acid by oxidation of p-cresol with atmospheric oxygen in an acetic acid-acetic anhydride mixture under catalysis of cobalt acetate, manganese(II) acetate, and sodium bromide (Litvintsev et al. 1994). This procedure ensures 60% yield of p-acetoxybenzoic acid and 100% conversion of the initial p-cresol. 

In contrast to p-cresol, o-cresol does not undergo oxidation under these conditions. The same restriction is true in the case of 4-hydroxy-3,4 -dimethylbiphenyl—only one methyl group undergoes oxidation, the one in position 4 (KosheF et al. 1997). The methyl group that is in position 3—ortho with respect to the hydroxy group—remains intact. Such inactivity is explained in terms of the cation-radical mechanism according to Scheme 7.50. 

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. 

Bossert ID, Young LY. 1986. Anaerobic oxidation of p-cresol by a denitrifying bacterium. Appl Environ Microbiol 52 1117-1122. 

The reaction of A -3-ketosteroids with 2,6-di-tertbutyI-p-cresol is specific, and different analytes yield various colors. In alkaline media and in the presence of an oxidant (e.g., hydrogen peroxide), A" -3,1 1-diketo steroids (such as cortisone and prednisone, at levels of 5-25 pg) develop yellow-orange colors with this reagent. 

The second pathway using VAO reported by van den Heuvel et al. [83] is the VAO-catalysed oxidation of vanillyl alcohol to vanillin. Vanillyl alcohol is not very abundant in nature but can be generated by VAO-catalysed conversion of creosol (2-methoxy-p-cresol). As creosol can be found in creosote obtained from heating wood or coal tar, the feedstock for this pathway is very abundant. 

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