Cracking Cresol

The oldest cresol production method used in the United States is through the recovery of fractional distillates from coal tars. Most domestic cresols are formed via catalytic and thermal cracking of naphtha fractions during petroleum distillation. Since 1965, quantities of coal tar and petroleum isolates have been insufficient to meet the rising demand. Consequently, several processes for the manufacture of the various isomers have been developed. One General Electric facility produces o-cresol at an annual capacity of 10,000 tons by the methylation of phenol in the presence of catalysts. The Sherman-Williams Company uses the toluene sulfonation process and maintains an annual capacity for p-cresol of 15,000 tons. The Hercules Powder Company produced p-cresol until 1972 by the cymene- cresol process. 

Little information is available concerning the composition of phenols from distillates of petroleum, though in certain instances they may be present in the acid mixtures in fairly high concentrations. However, phenol, Various alkyl phenols, and cresols have been separated from cracked distillates. 

Somewhat similar are the so-called adductive crystallization processes, often (wrongly) called extractive crystallization, where reactions of complex/ adduct formation are used to separate compounds that are otherwise difficult to separate. Examples of adductive crystallization include separation of p- and m-cresols (137), separation of o- and p - n i troch I oro ben zcn cs (138), separation of quinaldine and isoquinoline (139), separation of nonaromatic compounds from naphtha-cracking raffinate (140), and separation of p-cresol from 2,6-xylenol (141). Other examples of reactive crystallization/precipitation reported in the literature are listed in Table 5. 

Hydrocarbon waxes produced in a fixed-bed reactor, which has operated since 1955, have found a variety of uses. Also, byproducts from the Sasol Lurgi coal gasifiers are recovered for chemical and solvent applications. These products include phenol, cresols, toluene, xylenes, ammonia, and sulfur. An addition to the spectrum of chemical products from Sasol is polypropylene. Also, ethane is being cracked to supplement ethylene production for sale to polyethylene producers. Additional work is in progress to evaluate the recovery of organic acids from aqueous waste streams. 

In the USA, natural cresols and xylenols have been historically made from the naphtha fractions of catalytic, thermal cracking or even coking processes in the petroleum industry. These products contain to the tune of 1% Ce-Cs phenols [1,8]. 

In 1865 just prior to Kekule s synthesis of phenol, Joseph Lister (1827-1912) was experimenting with carbolic acid as an aid to antiseptic surgery which he had pioneered. A mixture of crystallised carbolic acid and shellac (lac plaster) was employed in the finally adopted mode of application. The requirement of phenol for the manufacture of picric acid during the Boer war and other uses resulted in a demand which soon outstripped the resources of phenol/cresols available from coal distillation. Synthetic phenol thus became a potentially important intermediate. The lengthy processing involved in the separation of phenol and the isomeric cresols led to the desirability for specific syntheses. In 1978 of the world production of phenol only 3% came from coal sources by extraction of the mixed phenols (about 1.5% in coal tar) with 10% sodium hydroxide, acidification with carbon dbxide and separation. Phenolic compounds are also formed during catalytic cracking processes in the petroleum industry. There are historically six industriai processes for the production of synthetic phenol, variously from benzene and toluene, some of which are also applicable to the cresols and the dihydric phenols. 

Couper, Archibald S., 3 Coupling constant (J), 503, 506, 507-508 dihedral angle dependence, 544 Covalent bond, 12-14, 44 Cracking, in petroleum refining, 70 Crafts, James M., 451 m-Cresol, 939 acidity of, 944... 

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