Cresol from toluene

Other examples of oxynitration include the formation of (1) 2,4,6-trinitro-m-cresol from toluene, (2) 2,4-dinitronaphth-l-ol from naphthalene, (3) 3-chloro-2,4,6-trinitrophenol from chlorobenzene and (4) 3-hydroxy-2,4,6-trinitrobenzoic acid from benzoic acid. ... 

The formation of cresols as traces, are also the consequence of the presence of water generated during the photoreaction in fact hydroxy radicals photogene rated from water can be attached to the aromatic ring of toluene leading to the formation of an intermediate radical which is further aromatized (refs.4 and 16) according to equation 1. The formation of cresols, from toluene, in non-aqueous media, have been also observed by other authors (ref.18) but after prolonged irradiation times. 

Traditionally, phenol is produced from benzene, cresols from toluene and xylenols from xylenes. There are three isomers of xylenes, namely, / -xylene, o-xylene, and m-xylenes. Accordingly, there are six isomers of xylenols which have been mentioned earher vide 1.1. Some of the properties of various xylenols have also been mentioned. Commercially, xylenols have assumed great significance. In some cases, xylenols can be used as substitutes of cresols. However, some of the individual xylenol isomers have importance in organic chemical synthesis. 

Though traditionally obtained from coal tar or from fractions during secondary refining processes of petroleum, they are also obtained as mixed xylenols from a mixture of xylenes CAS no. [1330-20-7] or as pure isomers from individual xylems i.e., m-xylene, o-xylene, or p-xylene. Process chemistry for production of xylenols from xylenes is similar to that of cresols from toluene (see Chapter 2), i.e., sulfonation of the respective aromatic hydrocarbons, followed by neutralization of the sulfonic acids, caustic fusion and acidification of the sodium/potassium salts and purification via distillation. Summary of principal properties of xylene isomers has been shown vide Table 1.1. 

Resorcinol, dihydroxy benzene, and naphthols both a and P, are the most important hydroxy-aromatics having wide applications and are produced from benzene and naphthalene, respectively, using similar technologies as in production of synthetic phenol from benzene or cresols from toluene. It may be relevant to discuss briefly about these products. 

It has been recently announced that technology for separation of para- and meto-cymenes is offered by Chiyoda Corporation in Yokohama, Japan through Kellog. As in the case of phenol from benzene via cumene, acetone is obtained as a co-product during production of cresols from toluene via cymenes. 

The Company, Gujarat Aromatics Limited, was making synthetic cresols from toluene but since the finished product, mixed cresols (cresylic acid) did not have sufficient market, more often than not the company s manufacturing facilities at Ankleshwar, Gujarat had to be shut down. The company was soon amalgamated with Atul Limited, a big multiproduct Chemical giant of Gujarat, and, was reconstituted as the Aromatics Division of Atul. 

Mixed cresols, also known as cresylic acids, the lowest among the alkyl phenols, were primarily produced as by-products from coal carbonization plants or recovered from the petroleum refinery caustic washes. These cresols obtained from natural sources were known to the chemical industry for the last 75 years and had limited uses. Production of synthetic cresols from toluene opened up new avenues for these products... 

Ferric chloride was omitted from the system and then replaced successively by either cupric sulfate, ceric sulfate, ferrous sulfate, or flavin mononucleotide (FMN). In each experiment the yield of methoxy-phenols from anisole was negligible. Other ferric salts, however, were found to induce hydroxylation (Table VIII). The addition of EDTA to the ferric chloride-NBNH system markedly reduced the yield of cresols from toluene. 

This can further react in different chaimels first is can give benzeneoxide QH5O, which is in equilibrium with oxepine - from which through photolysis phenols are gained, for example a-cresol from toluene. 

McNeil, D., Sulfonation of Toluene and Production of Cresols from Toluene, in Toluene the Xylenes and their Industrial Derivatives, E.G. Hancock, Editor, Elsevier, New York, 1982, p. 211. 

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. 

Methylphenol. y -Cresol is produced synthetically from toluene. Toluene is chlorinated and the resulting chlorotoluene is hydrolyzed to a mixture of methylphenols. Purification by distillation gives a mixture of 3-methylphenol and 4-methylphenol since they have nearly identical boiling points. Reaction of this mixture with isobutylene under acid catalysis forms 2,6-di-/ f2 -butyl-4-methylphenol and 2,4-di-/ f2 -butyl-5-methylphenol, which can then be separated by fractional distillation and debutylated to give the corresponding 3- and 4-methylphenols. A mixture of 3- and 4-methylphenols is also derived from petroleum cmde and coal tars. 

Methylphenol. T -Cresol is produced synthetically from toluene. Toluene is sulfonated to yield T i ra-toluenesulfonic acid, which is then converted to 4-methylphenol via the caustic fusion route. A minor amount of 4-methylphenol is also derived from petroleum cmde and coal tars. 4-Methylphenol [106-44-5] is available in 55-gal dmms (208-L) and in bulk quantities as a molten material. 

With aromatic compounds conditions can be found so that ring oxidation predominates and phenolic compounds are formed. Benzene is oxidized quantitatively to phenol. Toluene is oxidized to o-cresol, m-xy-lene to l,3-xylen-4-ol, and naphthalene to f-naphthol. The addition of certain additional catalyst, such as molybdenum oxide, promoted coupling reactions and biphenyl was formed from benzene, bi- or poly-tolyl hydrocarbons from toluene, di- and polyxylyls from wi-xylene, and a... 

Samples of your urine can be tested for the presence of cresols, although this test is not routinely available in hospitals and clinics. This test will not tell you whether or not you will have any adverse health effects. The urine sample would have to be taken within 1 day of your exposure to be valid. Because cresols occur naturally in people, ant at levels that very from one individual to the next, results from tests for cresol exposure should be compared to values obtained from the same individual either before exposure or several days after exposure. Small changes might be caused by variation in daily diet. You should also be aware that an increased presence of cresols in the urine could indicate exposure to toluene, a related compound, rather than cresols. However, toluene exposure would also result in elevated urinary levels of hippuric acid cresol exposure would not. 

In a general sense, the kinetics and metabolism of toluene in humans, rats and mice are very similar the hippurate is in all cases by far the major metabolite, while in all species the ortho- and / ora-cresols are minor metabolites. To what extent formation of a potentially reactive sulfate conjugate of benzyl alcohol occurs (van Doom et al., 1980 Chidgley et al., 1986) is uncertain, mainly because mercapturates formed from toluene have not been characterized. Similarly, whether the covalent binding observed in rat liver microsomes has any toxicological relevance is uncertain. 

In meats, of course, there are components which arise from the protein which cannot be present in the products from pure fat. Table III shows some of the sulfur compounds and aromatic compounds which are also found in irradiated meats. Many of these can be postulated as arising from direct bond cleavage of amino acid moieties. Benzene and toluene may come from phenylalanine and phenol and p-cresol from tyrosine. Recent studies have been directed to considering the origin of some of the compounds from proteinaceous substances. Some of the sulfides, disulfides, and mercaptans can derive directly from cysteine or methionine, but those containing more than two carbon atoms in a chain require more than a superficial explanation. In order to evaluate the contribution of the volatiles from the protein as well as the lipid constituents of meat, volatile components produced in various protein substances have also been analyzed. 

The electro-Fenton method (or EFR) was initially used for synthetic purposes considering the hydroxylation of aromatics in the cathodic compartment of a divided cell. Thus, the production of phenol from benzene (Tomat and Vecchi 1971 Tzedakis et al. 1989), (methyl)benzaldehydes and (methyl)benzyl alcohols from toluene or polymethylbenzenes (Tomat and Rigo 1976,1979,1984,1985) by adding Fe3+ to generate Fe2+ via reaction (19.13), as well as benzaldehyde and cresol isomers from toluene or acetophenone and ethylphenol isomers from ethylbenzene (Matsue et al. 1981) with direct addition of Fe2+, have been described. Further studies have reported the polyhydroxylation of salicylic acid (Oturan et al. 1992)... 

HDA [HydroDeAlkylation] A proprietary dealkylation process for making benzene from toluene, xylenes, pyrolysis naphtha, and other petroleum refinery intermediates. The catalyst, typically chromium oxide or molybdenum oxide, together with hydrogen gas, removes the methyl groups from the aromatic hydrocarbons, converting them to methane. The process also converts cresols to phenol. Developed by Hydrocarbon Research with Atlantic Richfield Corporation and widely licensed worldwide. 

Ring alkylation, as utilized in the manufacture of cresol from phenol, is suppressed and toluene selectivjiies arc liigh (40). 

Problem 24.5 Outline all steps in the synthesis from toluene of (a) / -cresol via diazotization (b) / -cresol via thallation (c) and (d) m-cresol via each route. Hint See Secs. 23.16 and 11.13.)... 

Other more prominent process for production of resorcinol is through alkylation of benzene using propylene in such as a way that alkylation is done carefully to introduce isopropyl in 1 and 3 position, i.e., diisopropyl benzene which is then converted to resorcinol using a similar process of phenol from isopropyl benzene or cresols from iosopropyl toluene. 

Mixed cresols are available in India both from coal and lignite carbonization plants and are also produced synthetically, particularly p-cresol, using toluene as the critical feedstock. 

Synthetic cresols production from toluene feedstock will be discussed in some details in a subsequent chapter. A brief review of cresols or cresylic acid production from coal/lignite is presented here. 

In other words ortho- and para-toluene sulphonyl chlorides are formed, which on high temperature hydrolysis produces ortho- and para-toluene sulfonic acids. This mixture on neutralization, caustic fusion, and acidification produces a mixture of ortho- and para-cresols. The resultant product contains approximately 85% p-cresol and 15% o-cresol from which pure para-cresol (99%- -) and pure ortho-cresol (99%-h) can easily be obtained. 

Because of somewhat lower boiling point compared to m-cresol andp-cresol, o-cresol is obtained as a co-product during fractionation of cresols from coal tar acids or during production of para-cresol based on sulfonation of toluene. Most of the p-cresol manufacturers such as PMC, INSPEC (now Laporte), Atul and others are producing o-cresol in the range of 600-1500 tpa depending on p-cresol production. 

Various academic and industrial research centers have tried to establish a viable process for separation of para-cresol from a mixture of meto-para-cresols after low boiling ortho-cresol and phenol have been removed from a cresol mix. This is true not only for synthetic cresols made from toluene but also from natural mixtures. 

The main by-products formed in the HDO reaction are ortho- and para-cresols (0.4 kg per t of phenol arising from toluene impurities of benzene feeding), cyclohexylbenzene (7.2 kg per t of phenol), biphenyl (4.4kg per t of phenol), dibenzofuran (3.2 kg per t of phenol) and condensed polycyclic aromatic hydrocarbons (25.2 kg pert of phenol). 

Toluene Urinary hippuric acid and o-cresol blood toluene can result from certain food additives... 

In the pyrolysis of proteins, the dominant mechanism is the splitting-off of the amino acids rather than break-up of the backbone into smaller fragments which are characteristic of the original amino acids.Usually highly characteristic signals are found for the aromatic and sulphur containing amino acids, e.g., hydrogen sulphide from cystine and in combination with methionine pyrrole pyrrolidine and methylpyrrole for proline, phenyl, and cresol from tyrosine, toluene, styrene and phenylacetonitrile for phenylalanine indole, and methylindol from tryptophan. 

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