Olefins metathesis chemistry

For a comprehensive review of metathesis chemistry, see Ivin KJ, Mol JC (1997) Olefin metathesis and metathesis polymerization, Academic, San Diego, London and references therein... 

This is a major achievement, mainly due to Basset and his group, in surface organometallic chemistry because it has been thus possible to prepare single site catalysts for various known or new catalytic reactions [53] such as metathesis of olefins [54], polymerization of olefins [55], alkane metathesis [56], coupHng of methane to ethane and hydrogen [57], cleavage of alkanes by methane [58], hydrogenolysis of polyolefins [59] and alkanes [60], direct transformation of ethylene into propylene [61], etc. These topics are considered in detail in subsequent chapters. 

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... 

Eleuterio, H. S., Scientific Discovery and Technological Innovation an Eclectic Odyssey into Olefin Metathesis Chemistry , J. Macromol. Sci. - Chem. A, 28, 907-915 (1991). 

Olefin metathesis is one of the few fundamentally new organic reactions discovered over the last few decades that has revolutionized organic and polymer chemistry. Olefin metathesis provides a convenient and rehable way to synthesize imsaturated molecules that are often hard to prepare by any other method. A munber of reviews [8-17] and books [18-20] have been published in this area, aU of which focus on the ever-increasing use of olefin metathesis in organic synthesis and polymer chemistry. Particularly in the latter research area, ROMP has become a powerful and popular method to synthesize polymers with narrow molecular weight distributions. Due to the hving nature of polymerizations initiated by state-of-the-art initiators, well-defined diblock, triblock or multiblock copolymers are available today. 

Metathesis of olefins, through the use of transition metal catalysis, is an important application in the petrochemical as well as in the polymer chemical industry for the production of special olefins and polymers (cf. Section 2.3.3). This chemistry is also applicable to unsaturated fatty acid esters, such as acetic acid methyl ester. However, the high price and unsustainability of the catalysts, compared with the fatty acids as substrates, have made commercial utilization not yet possible nevertheless they are of great interest for researchers in this field. 

C. L. Dwyer, Metathesis of Olefins, in Metal-Catalysis in Industrial Organic Processes. G. P. Chiusoli and P. M. Maitlis, Eds., Royal Society of Chemistry Colchester, UK, 2006. pp. 201-217. 

The advent of the energy crisis has caused us to examine traditional views of the relative costs of different monomers and to consider the potential of less costly monomers for polymerization. One can expect that catalysis of the coordinated anionic type will play a major role in any new developments in olefin and diene polymerizations. Finally, one should recall that Ziegler catalysts have found many uses in other areas of chemistry such as metathesis of olefins, oligomerization, isomerization, hydrogenation, and alkylation. The vast scope of these catalysts will almost certainly achieve a wider range as these types of studies continue in the future. 

The direct metathesis polymerization of acetylenes is not the only route to polyacetylenes using olefin metathesis chemistry. Below are summarized some of the other methods that have been developed in recent years. 

One of the most fascinating reactions of hydrocarbons to emerge in recent years is the catalyzed disproportionation or metathesis of olefins. First disclosed in 1964 ( 1), this versatile reaction has opened up a new and exciting field of hydrocarbon chemistry. It has been studied in research institutions throughout the world, resulting in more than 2000 publications, and has been the topic of four international symposiums ( ). Commercially, it is used for the interconversion of light olefinic hydrocarbons, the backbone of today s petrochemical industry, and for the synthesis of olefins for the specialty chemicals market (, . ... 

The chemistry of metal-to-carbon multiply bonded complexes continues to flourish. The critical role olefin metathesis chemistry now plays in so many areas of synthesis and materials science has provided important impetus for the continued discovery and study of such species. " While the scope of this contribution is far too narrow to even begin to touch upon this broad area of organometallic chemistry, the authors wish to highlight one new class of organometallic complexes that falls within this category, that of the terminally bonded carbides. 

In some cases, rapid a-elimination reactions have been observed. These reactions most often occur with early metal complexes and form metal-alkylidene complexes. However, examples of this elimination process from complexes of later transition metals are now known. a-Eliminations from carbene complexes to form carbyne complexes and from amide complexes to form imido complexes are also now well established. Although a-eliminations typically occur with complexes that cannot undergo 3-hydrogen elimination, complexes are now known that undergo faster a-hydrogen elimination than p-hydro-gen elimination. Such a-elimination reactions give rise to the metal-alkylidene complexes that catalyze the olefin metathesis chemistry described in Chapter 21. 

Buffon, R., Choplin, A., Leconte, M., Basset, J.-M., Touroude, R. and Herrmann, W. A., (1992) Surface organometallic chemistry of rhenium attempts to characterize a surface carbene in metathesis of olefins with the catalyst CH3Re03/Nb205, J. Mol. Catal. 72, L7-LIO. 

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