Phenol is a colorless solid crystal structure with a very specific smell.This substance is widely used in the manufacture of various dyes, plastics and various synthetic fibers (mostly nylon).Before the development of petrochemical industry in the production of phenol was carried out exclusively from coal tar.Of course, this method was not able to cover all the needs of a booming industry in phenol, which has now become an important component of almost all the objects around us.
Phenol, the preparation of which has become a necessity due to the emergence of an extremely wide range of new materials and compounds, an essential ingredient in which it is used in the synthesis of phenol-formaldehyde resin.And she, in turn, is an important component phenoplasts.Also a large amount of phenol is converted into cyclohexanol required to manufacture synthetic fibers on an industrial scale.
more important applications can be distinguished production of phenol cresol mixture, which is synthesized in kreozolformadelgidnuyu resin used for the manufacture of a plurality of medicines, antiseptics and antioxidants.Today, therefore, to obtain large amounts of phenol is an important task petrochemicals.Already it developed many methods to produce this substance in sufficient quantities.Let us consider the main ones.
oldest and most proven method is a method of alkali fusion, which is characterized by a high consumption of sulfuric acid sulfonation of benzene and caustic soda followed by fusing them benzolsulfonatrievuyu salt, from which stands out immediately and the substance.Getting phenol by chlorination of benzene and chlorobenzene, followed by saponification with sodium hydroxide is profitable only in the event of large quantities of cheap electricity needed to produce chlorine and caustic soda.The main disadvantages of this method - the need to create high pressure (not less than three hundred atmospheres), and an extremely large amount of corrosion of equipment.
more modern method is to obtain phenol by the decomposition of cumene hydroperoxide.However, the scheme of allocation of the desired material is quite complex, as it provides pre-production of hydroperoxide way alkylation of benzene with propylene solution.Further, the technology provides for the oxidation of the resulting isopropyl air mixture to form a hydroperoxide.As a positive factor of this technique can be noted in parallel with phenol receiving another important matter - acetone.
There is also a method of separating phenol from coke and semi-coke tar solid fuels.Such a procedure is needed not only to produce valuable phenol, but also to improve the quality of various hydrocarbon products.One property is the rapid oxidation of phenol, which leads to accelerated aging and the formation of oil therein viscous tar-like fractions.
But the most modern methods and the latest achievement of the petrochemical industry is to obtain phenol directly from benzene by oxidation of its nitrous oxide.The entire process is performed in special adiabatic reactor, wherein the catalyst is zeolite.The initial nitrous oxide produced by oxidation of ammonia with air or release of adipic acid.More specifically, of its side products formed during synthesis.This technology is able to ensure production of high-phenol with a minimum total content of impurities.
