Cresol compounds

The most common method for GC/MS analysis of semivolatile compounds (EPA SW-846 8270) includes 16 polycyclic aromatic compounds, some of which commonly occur in middle distillate to heavy petroleum products. The method also quantifies phenols and cresols, compounds that are not hydrocarbons but may occur in petroleum products. Phenols and cresols are more likely found in crude oils and weathered petroleum products. 

Atkinson 1988) and either of the rate constant values, the estimated half-life of the DNOC reaction with OH radicals is >77 days. Since dinitrocresols are expected to be present predominantly in the particulate phase in the atmosphere, the reaction rate will be even slower compared to the gas phase reaction rate (Grosjean 1991). The reactions of phenol and cresols with No radicals may be significant processes in the air (Atkinson et al. 1992). However, the products of these reactions with phenol or cresols are o- and possibly p-substituted nitrophenol and cresol compounds (Atkinson et al. 1992). Since both o and p positions are already occupied by nitro substituentes, the reaction of DNOC with NO3 radicals does not seem to be a significant atmospheric process. 

Cresol, fumes - 190, 201 Cresol, xylene solution - 156 Cresolic compounds - 233... 

Cresoi cresolic compounds 22 7 5 Moderate resistance-some visual change (discoloration/crazing/ checking) occurs Chemical resistance per ASTM D543 Lustrex Monsanto Specimen 50.8 mm (2 in) diameter discs... 

The solution must be strongly acid in order to avoid the coupbng reaction between the undecomposed diazonium salt and the phenol (see under Azo Dyes). For the preparation of phenol and the cresols, the aqueous solution of the diazonium compound is warmed to about 50° at higher temperatures the reaction may become unduly vigorous and lead to appreciable quantities of tarry compounds... 

Thio-p-cresol (p-tolyl mercaptan), p-CHjCjH SH. This compound may be similarly prepared from p-toluenesulphonyl chloride (Section IV,207). The thio-p-cresol crystallises in the steam distillate and is collected and dried m.p. 43°. The b.p. under normal pressure is 194r-195°. 

Separations based upon differences in the chemical properties of the components. Thus a mixture of toluene and anihne may be separated by extraction with dilute hydrochloric acid the aniline passes into the aqueous layer in the form of the salt, anihne hydrochloride, and may be recovered by neutralisation. Similarly, a mixture of phenol and toluene may be separated by treatment with dilute sodium hydroxide. The above examples are, of comse, simple apphcations of the fact that the various components fah into different solubihty groups (compare Section XI,5). Another example is the separation of a mixture of di-n-butyl ether and chlorobenzene concentrated sulphuric acid dissolves only the w-butyl other and it may be recovered from solution by dilution with water. With some classes of compounds, e.g., unsaturated compounds, concentrated sulphuric acid leads to polymerisation, sulphona-tion, etc., so that the original component cannot be recovered unchanged this solvent, therefore, possesses hmited apphcation. Phenols may be separated from acids (for example, o-cresol from benzoic acid) by a dilute solution of sodium bicarbonate the weakly acidic phenols (and also enols) are not converted into salts by this reagent and may be removed by ether extraction or by other means the acids pass into solution as the sodium salts and may be recovered after acidification. Aldehydes, e.g., benzaldehyde, may be separated from liquid hydrocarbons and other neutral, water-insoluble hquid compounds by shaking with a solution of sodium bisulphite the aldehyde forms a sohd bisulphite compound, which may be filtered off and decomposed with dilute acid or with sodium bicarbonate solution in order to recover the aldehyde. 

Under the same conditions the even more reactive compounds 1,6-dimethylnaphthalene, phenol, and wt-cresol were nitrated very rapidly by an autocatalytic process [nitrous acid being generated in the way already discussed ( 4.3.3)]. However, by adding urea to the solutions the autocatalytic reaction could be suppressed, and 1,6-dimethyl-naphthalene and phenol were found to be nitrated about 700 times faster than benzene. Again, the barrier of the encounter rate of reaction with nitronium ions was broken, and the occurrence of nitration by the special mechanism, via nitrosation, demonstrated. 

NMR spectrum of 3 methylphenol m cresol) Notice that contrary to what we might expect for a compound with seven peaks for seven different carbons the intensities of these peaks are not nearly the same The two least intense signals those at 8 140 and 8 157 correspond to carbons that lack attached hydrogens... 

An old name for benzene was phene and its hydroxyl derivative came to be called phe nol This like many other entrenched common names is an acceptable lUPAC name Likewise o m and p cresol are acceptable names for the various ring substituted hydroxyl derivatives of toluene More highly substituted compounds are named as deriv atives of phenol Numbering of the ring begins at the hydroxyl substituted carbon and proceeds m the direction that gives the lower number to the next substituted carbon Sub stituents are cited m alphabetical order... 

Infrared The IR spectra of phenols combine features of those of alcohols and aro matic compounds Hydroxyl absorbances resulting from O—H stretching are found m the 3600 cm region and the peak due to C—O stretching appears around 1200-1250 cm These features can be seen m the IR spectrum of p cresol shown m Figure 24 3... 

Other routes for hydroxybenzaldehydes are the electrolytic or catalytic reduction of hydroxybenzoic acids (65,66) and the electrolytic or catalytic oxidation of cresols (67,68). (see Salicylic acid and related compounds). Sahcylaldehyde is available in drums and bulk quantities. The normal specification is a freezing point minimum of 1.4°C. 4-Hydroxybenzaldehyde is available in fiber dmms, and has a normal specification requirement of a 114°C initial melting point. More refined analytical methods are used where the appHcation requires more stringent specifications. 

Triaryl phosphates are produced by reaction of phosphoms oxychloride with phenoHc compounds at 100—200°C with magnesium or aluminum chloride catalyst. Past use of cresols and xylenols from coal tar or petroleum is replaced for lower toxicity and cost by synthetic phenoHcs, primarily isopropyl phenol, /-butyl phenol, and phenol itself A range of viscosities is achieved by selection and proportioning of the phenols and their isomers used for the starting material. 

Additives. Compounds are often added to the polymer at the extmder or melt homogenizer. Common additives are antioxidants (qv), thermal stabilizers, sHp agents, antiblock agents, anduv stabilizers. Popular antioxidants are 2,6-di-/-butyl-/)-cresol (BHT), octadecyl... 

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). 

Stabilization of Fuels and Lubricants. Gasoline and jet engine fuels contain unsaturated compounds that oxidize on storage, darken, and form gums and deposits. Radical scavengers such as 2,4-dimethyl-6-/ f2 butylphenol [1879-09-0] 2,6-di-/ f2 -butyl-/)-cresol (1), 2,6-di-/ f2 -butylphenol [128-39-2], and alkylated paraphenylene diamines ate used in concentrations of about 5—10 ppm as stabilizers. 

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). 

Guaiacols. Cresote, obtained from the pyrolysis of beechwood, and its active principles guaiacol [90-05-1] (1) and cresol [93-51-6] (2) have long been used ia expectorant mixtures. The compounds are usually classed as direct-acting or stimulant expectorants, but their mechanisms of action have not been well studied. Cresol is obtained by the Clemmensen reduction of vanillin (3), whereas guaiacol can be prepared by a number of methods including the mercuric oxide oxidation of lignin (qv) (4), the ziac chloride reduction of acetovanillone (5), and the diazotization and hydrolysis of o-anisidine (6). 

Oxidation of /U-cresol afforded a triphenol 22 which is approximately half the molecule. The central hydroxyl of the triphenol could be selectively methylated and then the compound was ort/ro-brominated and bridged using 1,3-dibromopropane to give 23. Metallation with butyllithium followed by iron catalyzed coupling afforded the macrocycle as indicated. 

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