Industrial Synthetic Methods

Although coal tar is still an industrial source of phenol and the three cresols (methylphenols), e.g. m-cresol (2), and the dimethyl derivatives (xylenols), synthetically manufactured material predominates. 

Phenol, previously known as carbolic acid, is both corrosive to human tissue and poisonous and 

Cumene is obtained from benzene by Friedel-Crafts alkylation with propene. 

Hemiacetals or hemiketals are usually formed by the acid-catalysed addition of an alcohol to the carbonyl group of an aldehyde or ketone, e.g. 

Chlorobenzene, commercially produced by the Raschig process (see p. 108), is resistant to nucleophilic substitution under normal conditions, but in the Dow process, treatment with sodium hydroxide at 300 °C under high pressure is effective. Phenol may also be prepared from chlorobenzene by reaction with steam at 450 °C over a catalyst. 

Phenol, previously known as cartjoiic add, is both coriosive to tiuman tissue and poisonous and care is needed in its handling. It is an important industriai compound witii many uses, a major one being in the produrttior of ijheriol-formaldehyde polymers Such as Bakelite. 

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Benzene, naphthalene, toluene, and the xylenes are naturally occurring compounds obtained from coal tar. Industrial synthetic methods, called catalytic reforming, utilize alkanes and cycloalkanes isolated from petroleum. Thus, cyclohexane is dehydrogenated (aromatization), and n-hexane(cycli> zation) and methylcyclopentane(isomerization) are converted to benzene. Aromatization is the reverse of catalytic hydrogenation and, in the laboratory, the same catalysts—Pt, Pd, and Ni—can be used. The stability of the aromatic ring favors dehydrogenation. 

Oxidized paraffin soaps can be synthesized by adopting petroleum paraffin as raw material. Because synthetic reaction of oxidized paraffin is relatively simple, oxidized paraffins are widely applied in industry. Synthetic methods of oxidized paraffin comprise air oxidation process and NO2 oxidation process. Air oxidation process is widely applied. In general, petroleum paraffin is heated to 150 or above in the presence of O2 and KMn04. The oxidation reactions can be given by ffie following ... 

The direct carboxylation of alkanes by CO to give carboxylic acids is a very attractive transformation [12-15, 18-22], as aliphatic carboxylic acids are important commodity chemicals [27], However, their industrial synthetic methods still represent a number of limitations [20, 27], such as the use of relatively expensive olefins and aldehydes as starting materials, the requirement of harsh reaction conditions, multistage transformations, and expensive metal catalysts. 

The new synthetic route to ibuprofen is an important example of how ideas of green chemistry can influence for the better the industrial synthetic methods used, not only from the point of view of economic efficiency, but also by introducing more effective methods of science and technology. Improved methods of synthesis for hexan-l,6-dioic acid (adipic aid) and cis-butenediol acid (maleic anhydride) - important for the industrial synthesis of nylon and polyesters respectively - are two other examples of the impact of a greener synthetic approach to industrial chemistry. 

Catalytic asymmetric hydrogenation was one of the first enantioselective synthetic methods used industrially (82). 2,2 -Bis(diarylphosphino)-l,l -binaphthyl (BINAP) is a chiral ligand which possesses a Cg plane of symmetry (Fig. 9). Steric interactions prevent interconversion of the (R)- and (3)-BINAP. Coordination of BINAP with a transition metal such as mthenium or rhodium produces a chiral hydrogenation catalyst capable of inducing a high degree of enantiofacial selectivity (83). Naproxen (41) is produced in 97% ee by... 

As is the case with most specialty organic compounds, pyridine sales are generally not pubHcized, and industrial processes for their manufacture are either retained as trade secrets or patented (see Patents and trade secrets). Up to about 1950, most pyridines were isolated from coal-tar fractions however, after 1950 synthetic manufacture began to take an ever-increasing share of products sold. By 1988, over 95% of all pyridines were produced by synthetic methods. 

Until the late 1890s, coumarin was obtained commercially from only natural sources by extraction from tonka beans and deer tongue. Then synthetic methods of preparation and industrial manufacturing processes were discovered and developed starting principally from o-cresol, phenol, and sahcylaldehyde. Various methods can be used to obtain coumarin from each of these starting materials. 

Combinatorial chemistry, a new chapter of organic synthesis, is now developing rapidly. This new approach to synthesizing large designed or random chemical libraries through application of solid phase synthetic methods, promises to revolutionize the process of drug discovery in the pharmaceutical industry.24... 

Malic add has a limited use in the food industry as an addifying agent where it is an alternative to dtric add. In nature, only L(-) malic add is found whereas the relatively cheap, chemical synthetic methods yield D/L mixtures. The favoured industrial way to produce the L(-) add is by enzymic transformation from fumaric add. Either whole cells or isolated and immobilised enzymes can be used, with high conversion effidendes. 

Functionalized polyethylene would be of great industrial importance, and if synthetic methods to control the microstructure of functionalized polymers using transition-metal-based catalysis are developed, it would significantly broaden the utility and range of properties of this class of polymers. Recent progress in the field of late transition metal chemistry, such as Brookliart s use of nickel-based diimine catalysts, has enabled the copolymerization of ethylene with functional a-olefins.29 However, these systems incorporate functionalized olefins randomly and with limited quantity (mol percent) into the polymer backbone. 

The industrial production of fatty acids on the basis of petrochemical raw materials is of secondary importance in comparison with their preparation from natural materials. Only short-chain or branched or odd-numbered carboxylic acids, for which natural sources don t exist, have to be prepared by different synthetic methods. 

The synthetic method used in preparing a particular boride phase depends primarily on its intended use. Whereas for basic research borides of high purity are desirable, for industrial applications, e.g., in coatings, tools and crucibles, as a refining agent in metallurgy or in control rods in nuclear energy plants, pure borides are unnecessary. 

At the time of its discovery in 1970, few chemical methods were known for the laboratory syntheses of such molecules. Fewer still were appropriate for their industrial scale production. Unlike many other amino acid derivatives, gl rphosate is stable in strong acid or base, even at elevated temperatures. It can also tolerate strong reductants and some oxidants (1,2). This stability accounts for the diversity of synthetic methods that have been explored and developed to prepare glyphosate and its heterocyclic derivatives over the last 25+ years. 

As the chemical industry expanded, Perkin continued his own scientific research in the peace of his private laboratory. He had not lost his touch. Among the synthetic methods he discovered is one now called the Perkin reaction. He used it to make a synthetic substitute for a vegetable substance called coumarin, which has a pleasant, vanillalike odor. Coumarin spawned the synthetic perfume business and made luxurious scents available to all. Once again, a Perkin chemical started a new industry, albeit a modest one in comparison with dyes and pharmaceuticals. Despite the worldwide impact of Perkins discoveries, he was not knighted by the British monarchy until 1906, the fiftieth anniversary of his discovery of mauve. The world chemistry community feted him lavishly that year, and he traveled to the United States collecting further honors. A year later, at the age of 69, he died peacefully, at home. 

As new synthetic methods are pursued in future to synthesize dendrimers more efficiently and cheaply on an industrial scale, one of the most promising areas for these macromolecules is seen in the construction of higher order assemblies or dendritic networks [213]. 

This chapter covers both traditional and more recent synthetic methods of preparing phosphors. It is important to note that as phosphors are used in all types of display, and are, therefore, an important part of a multibillion-dollar industry research and development is always ongoing to improve light output and, therefore, ease of viewing. The same is also true in the use of phosphors for lighting. 

Formation of 2,7-octadienyl alcohol (32) by the reaction of water has attracted much attention as a novel practical synthetic method for n-octanol, which is of considerable industrial importance. However, the reaction of water under usual conditions of the butadiene telomerization is very sluggish. Atkins, Walker, and Manyik found that the presence of a considerable amount of carbon dioxide showed a very favorable effect on the telomerization of water (40). Reaction of water (2.0 moles) with butadiene (1.0 moles) using Pd(acac)2 and PPh3 as the catalyst was carried out in the presence of carbon dioxide (0.5 mole) at 80-90°C. tert-Butyl alcohol, acetone, and acetonitrile were used as solvents. The products that were obtained are shown in Eq. (21) and Table I. 

The sulfoxidation of aliphatic hydrocarbons is the easiest method for the synthesis of alkylsulfonic acids. Their sodium salts are widely used as surfactive reactants in technology and housekeeping. Platz and Schimmelschmidt [1] were the first to invent this synthetic method. Normal paraffins (Ci4-Cig) are used for the industrial production of alkylsulfonic acids [2-4]. Olefins and alkylaromatic hydrocarbons do not produce sulfonic acids under the action of sulfur dioxide and dioxygen and retard the sulfoxidation of alkanes [5-9],... 

The pivotal role of natural a-amino acids among a myriad of biologically active molecules is widely appreciated, and is of particular importance in the pharmaceutical industry. Unnatural a-amino acids also have a prominent position in the development of new pharmaceutical products. It has been shown that substitution of natural a-amino acids for unnatural amino acids can often impart significant improvements in physical, chemical and biological properties such as resistance to proteolytic breakdown, stability, bioavailability, and efficacy. One of the many synthetic methods available for the production of enantiomerically enriched a-amino acids is the metal-catalyzed enantioselective reduction of a-de-hydroamino acid derivatives [90]. 

Later in his career, Nagata s group made notable and useful synthetic contributions to the beta lactam field. This included developing an economically feasible synthetic method for the industrial manufacture of 1-oxacephems from penicillin G. These efforts led to the worldwide introduction in the 1980s of several clinically prominent and effective beta lactam antibiotics of the 1-oxacephem class including moxalactam. 

Indirect electrochemical methods have been intensively studied, especially from the viewpoint of development of innovative synthetic methods in industrial organic chemistry. The indirect procedure is required when the direct method is unsuitable because (1) the desired reaction does not proceed sufficiently because of an extremely slow reaction or a very low current efficiency (2) the electrolysis lacks product-selectivity and thus offers only a low yield (3) tar and products cover the surface of the electrode, interrupting the electrolysis. Indirect electrochemical techniques involve the recycling of mediators (or electron carriers) in a redox system, as depicted in Fig. 1 [1-24]. 

Isomerization is a frequent side-reaction of catalytic transformations of olefins, however, it can be a very useful synthetic method, as well. One of the best-known examples is the enantioselective allylamine enamine isomerization catalyzed by [Rh (jR)-or(S)-BINAP (COD)] which is the crucial step in the industrial synthesis of L-menthol by Takasago [42]... 

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