Industrial applications olefins synthesis

Further important industrial applications of olefin metathesis include the synthesis of 3,3-dimethyl-l-butene ( neohexene , intermediate for the production of musk perfume) from ethene and 2,4,4-trimethyl-2-pentene, the manufacture of a,co-dienes from ethene and cycloalkenes (reversed RCM), and the ROMP of cyclooctene and norbomene to Vestenamer and Norsorex , respectively. 

Peroxidases have been used very frequently during the last ten years as biocatalysts in asymmetric synthesis. The transformation of a broad spectrum of substrates by these enzymes leads to valuable compounds for the asymmetric synthesis of natural products and biologically active molecules. Peroxidases catalyze regioselective hydroxylation of phenols and halogenation of olefins. Furthermore, they catalyze the epoxidation of olefins and the sulfoxidation of alkyl aryl sulfides in high enantioselectivities, as well as the asymmetric reduction of racemic hydroperoxides. The less selective oxidative coupHng of various phenols and aromatic amines by peroxidases provides a convenient access to dimeric, oligomeric and polymeric products for industrial applications. 

Olefin metathesis chemistry has had a profound impact in several areas of chemical research, including organome-tallics, polymer chemistry, and small molecule synthesis,many of which have industrial applications. For example, CM is currently utilized in the commercial preparation of several agrochemicals, polymer and fuel additives, and pharmacophores. Unlike RCM reactions, which are typically conducted under dilute... 

Olefin isomerization (Continued) industrial applications, 9, 95 ligand synthesis, 96 rhodium-catalyzed, 98 Olefins ... 

The synthesis of vitamin A was certainly a pioneering work in the industrial application of the Wittig reaction 6). The decisive step in this synthesis performed by the BASF, which had already established a plant for the production of vitamin A in 1971 2S4), is the Wittig olefination of vinyl-P-ionol 503 with y-formylcrotyl acetate 507 to vitamin A acetate 508. The phosphonium salt 505 is obtained by reaction of the alcohol 503 with triphenylphosphine hydrobromide 504 2S5) (Scheme 85). 

Over the past 25 years, biomimetic model systems have been extensively studied and a wide variety of interesting oxidation processes such as the epoxidation of olefins, the hydroxylation of aromatics and alkanes, the oxidation of alcohols to ketones, etc., have been accomplished some of these are also known in enantioselective versions with spectacular ee s. The vast majority of these transformations were obtained using monooxygen donors such as those mentioned above as primary oxidants. The complexity of the catalysts and the practical impossibility to use dioxygen as the terminal oxidant have so far prevented the use of such systems for large industrial applications, but some small applications in the synthesis of chiral intermediates for pharmaceuticals and agrochemicals, are finding their way to market. 

This species, completely characterized also by X-ray diffraction studies as its tetrahexylammonium salt (Figure 1)5 was responsible for the epoxidation of a series of structurally diversified olefins with typical selectivities of ca. 95% and chemical yields in the range 85-95%. These catalysts have found industrial applications in the epoxidation of alkenes and in the oxidative cleavage of alkenes to carboxylic acids. The favourable characteristics of these catalysts are thermal stability, ease of synthesis, stability to oxidation, solubility- in both water and organic solvents, effectiveness as phase transfer catalysts. 

In addition to the above described procedures implying either direct oxidation of an olefinic double bond or stereoselective reduction of a ketone precursor, which, as discussed above, do not really provide very efficient ways for the large scale synthesis of enantiopure epoxides, some indirect strategies have also been explored. These are essentially based on the resolution of epoxide-ring bearing substrates as exemplified below. As will be seen, these approaches imply the use of cofactor-independent enzymes, which are in practice much easier to work with, and lead to very interesting results. As a matter fact, some of these processes are already used on an industrial scale, and it can be predicted that future industrial applications will continue to be essentially based on the use of these very promising easy-to-use biocatalysts. 

The catalytic addition of CO and H2 (synthesis gas) to olefins (hydroformylation or oxo-synthesis) is one of the major industrial applications of homogeneous catalysis. Over 6 million metric tons of aldehydes or alcohols (oxo-products) are produced worldwide per year. Commodities based on the C4 oxygenates currently have... 

Perhaps the most basic form of the olefin metathesis reaction is the cross metathesis (CM) of acyclic olefins to yield new acyclic olefins (Fig. 4.11). The ratio of CM products may be controlled by steric and electronic factors to provide one product preferentially, rather than a statistical mixture, which is key to the synthetic utility of this reaction. For example, various functionalized olefins, dimers with bioactive substituents, and trisubstituted olefins have all been made by CM [33], and one of the industrial applications is the synthesis of insect pheromones [34]. 

Technology for a number of applications of olefin metathesis has been developed (, fO At Phillips, potential processes for producing isoamylenes for polyisoprene synthesis and long-chain linear olefins from propylene have been through pilot plant development. In the area of specialty petrochemicals, potential industrial applications include the preparation of numerous olefins and diolefins. High selectivities can be achieved by selection of catalyst and process conditions. The development of new classes of catalysts allows the metathesis of certain functional olefins (, 14). The metathesis of alkynes is also feasible (15) ... 

Wittig olefination was discovered in 1953 during studies on the reactions of pentaphenyl-phosphorane, and was described in the following year as a widely suitable method for olefin synthesis [33]. As early as 1956 a patent application appeared [34], in which the synthesis of retinoic acid esters from p-ionylideneacetaldehyde and (3-alkoxycarbonyl-2-methyl)allyl-triphenylphosphonium bromide was claimed, evidence of the fact that the inventors had rapidly realized the economic potential and industrial practicability of this novel reaction [35,36]. 

Among other applications olefin metathesis is useful in the synthesis of cyclic alkenes, the industrial preparation of propene, and in polymerization. 

The Julia olefination found its first industrial application for the produdion of retinoic acid. [74, 75] The original design ofthe synthesis, however, concealed a difficulty The allyl anion, substituted on both sides with electron-accepting substituents, does not react regioselectively. 

Clerici, M.G. and Kholdeeva, O.A. (eds) (2013) Liquid Phase Oxidation via Heterogeneous Catalysis Organic Synthesis and Industrial Applications, John Wiley Sons, Inc., Hoboken. Bruckner, A. and Baems, M. (1997) Selective gas-phase oxidation of polycyclic aromatic hydrocarbons on vanadium oxide-based catalysts. Appt Catal. A- Gen., 157 (1-2), 311-334. Corma, A., Esteve, P., and Martinez, A. (1996) Solvent effects during the oxidation of olefins and alcohols with hydrogen peroxide on Ti-beta catalyst the influence of the hydrophilicity-hydrophobicity of the zeolite. /. Catal, 161 (1), 11-19. 

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