Cresol, para

Para-cresol, which is also a constituent of coal-tar creasote, occurs in the es ential oils of jasmin and cassie flowers. It is a crystalline sub-... 

Para-cresol methyl ether occurs naturally in oil of ylang-ylang and similar flower oils. It is also prepared synthetically, and forms a useful artificial perfume for compound flower odours. It is a liquid boiling at 175°, and, as stated above, yields anisic acid on oxidation. 

Alkyl-substituted phenols have different reactivities than phenol toward reaction with formaldehyde. Relative reactivities determined by monitoring the disappearance of formaldehyde in phenol-paraformaldehyde reactions (Table 7.3) show that, under basic conditions, meta-cresol reacts with formaldehyde approximately three times faster titan phenol while ortho- and para-cresols react at approximately one-third the rate of phenol.18 Similar trends were observed for the reactivities of acid-catalyzed phenolic monomers with formaldehyde. 

PAR. See Polyarylate (PAR) para-Cresol (p-cresol), 384-385 para-Cresol novolac resin, 425 Paraformaldehyde, 377, 398 Para-para methylene linkages, 393, 395,... 

In a similar approach, double deprotonation of r 6-coordinated ortho- and para-cresols, 30 and 31, with t-BuOK led to formation of stable r 4-coordinated p- and o-quinone methide complexes of manganese, 32 and 33 (Scheme 3.19).37... 

See also para- Cresol para-Cresol, 25 185 Crestor, 5 143... 

Gibbard, H.F. andCreek,J.L. Vapor pressnre of methanol from 288.15 to 337.65K,/ Chem. Eng. Data, 19(4) 308-310,1974. Gibbs, H.D. para-Cresol. A new method of separating para-cresol from its isomers and a study of the boiling point, J. Am. Chem. Soc., 49(3) 839-844, 1927. 

The polarized signals correspond to the starting ester (30), the ortho-rearranged product (31) and para-cresol (32). The variation in intensity of the signals... 

Three types of closely related cresols exist ortho-cresol (o-cresol), meta- cresol (m-cresol), and para-cresol (p-cresol). Pure cresols are colorless chemicals, but they may be found in brown mixtures such as creosote and cresylic acids (e.g., wood preservatives). Because these three types of cresols are manufactured separately and as mixtures, they can be found both separately and together. Cresols can be either solid or liquid, depending on how pure they are pure cresols are solid, while mixtures tend to be liquid. Cresols have a medicinal smell (odor) and when dissolved in water, they give it a medicinal smell and taste. Cresols do not evaporate quickly from water, but in rivers and lakes, they can be removed quickly by bacteria. Dissolved cresols can pass through soil into underground water sources. This may be a problem at hazardous waste sites where cresols are buried. Once cresols are in the water table, they may stay there for months without changing. Cresols in air quickly change and break down into smaller chemicals, some of which irritate the eyes. Cresols can also irritate the eyes. 

Hazleton Labs. 1988d. Mutagenicity tests on meta-cresol and para-cresol inthe in vitro transformation of BALB/C-3T3 cells assay. Unpublished datasubmitted to EPA/OTS. Fiche no. OTS0517694. 

Hazleton Labs. 1989b. Dominant lethal assay in mice Para cresol CP945.HLA study no. 10003-0-471. Unpublished data submitted to ChemicalManufacturers Association, Washington, DC. 

Titton Bionetics. 1980a. Sister chromatid exchange assay, Ames assay, mouse lymphoma forward mutation assay, and transformation assay for a sample containing 33-1/3% each ortho-, meta-, and para-cresol. Unpublished data submitted to EPA/OTS. Fiche no. OTS0517528. 

MBA. 1988b. Subchronic toxicity of para-cresol in Sprague Dawley rats. Unpublished data submitted by Microbiological Associates to EPA. 

The Lurgi gasifiers used by Sasol operate at "low" temperatures and consequently phenols, and "tars" are "distilled" from the coal at the top of the gasifier, and carried out with the raw gas. On condensation two liquid phases are formed, "tar" and "gas liquor" (water). The "tar acids" (phenol, cresols etc) are dissolved in the "gas liquor" which is fed to the Phenosolvan unit where the acids are recovered by counter current extraction with butyl acetate or diisopropyl ether. The crude tar acids are fractionated to yield phenol, ortho, meta and para cresol and xylenols. The phenol is further refined to produce a high purity, colourless and stable product. Phenol is used mainly in the production of formaldehyde resins while the cresols are used as flotation frothers and in the manufacture of pesticides etc. 

Rubber antioxidants are commonly of an aromatic amine type, such as dibeta-naphthyl-para-phenylenediamine and phenyl-beta-naphthylamine. Usually, only a small fraction of a percent affords adequate protection. Some antioxidants arc substitute phenolic compounds (butylatcd hydro -vamsole, di-tert-butyl-para-cresol, and propyl gallate). 

In contrast to para-cresol, ortho-cresol does not undergo oxidation under these conditions. The same restriction holds in the case of 4-hydroxy-3,4 -dimethylbiphenyl Only one methyl group undergoes oxidation, the one in position 4 (KosheT 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 (Scheme 6-43). 

If ortho-, meta- and para-cresol concentrations cannot be differentiated, the total cresol concentration is used. 

---