Ethylene self-metathesis

Mo(CO)6/Al203 was found to be inert to self-metathesis of ethylenes... 

Self-Metathesis of Ethylenes over Re207/ A1203°... 

Macrocyclization of esters of allylglycine with diols has been successfully used to prepare derivatives of 2,7-diaminosuberic acid [861,864]. The latter are surrogates of cystine, and therefore of interest for the preparation of peptide mimetics. For unknown reasons protected allylglycine derivatives can not be directly dimerized by self metathesis [864]. However, catechol [864], ethylene glycol [861], and 1,2- or 1,3-di(hydroxymethyl)benzene derivatives [860] of allylglycine are suitable templates for the formal self metathesis of this amino acid via RCM. 

Cross-metathesis, however, is usually a nonselective reaction. Transformation of two terminal alkenes in the presence of a metathesis catalyst, for instance, can give six possible products (three pairs of cis/trans isomers) since self-metathesis of each alkene and cross-metathesis occur in parallel. It has been observed, however, that terminal olefins when cross-metathesized with styrene yield trans-P-alkylstyrenes with high selectivity.5 A useful synthetic application of cross-metathesis is the cleavage of internal alkenes with ethylene called ethenolysis to yield terminal olefins ... 

A number of new processes exploiting metathesis have been developed by Phillips. A novel way to manufacture lubricating oils has been demonstrated.145 The basic reaction is self-metathesis of 1-octene or 1-decene to produce Ci4-C28 internal alkenes. The branched hydrocarbons formed after dimerization and hydrogenation may be utilized as lubricating oils. Metathetical cleavage of isobutylene with propylene or 2-butenes to isoamylenes has a potential in isoprene manufacture.136,146 High isoamylene yields can be achieved by further metathesis of C6+ byproducts with ethylene and propylene. Dehydrogenation to isoprene is already practiced in the transformation of isoamylenes of FCC C5 olefin cuts. 

Metathesis is a versatile reaction applicable to almost any olefinic substrate internal, terminal or cyclic alkenes, as well as dienes or polyenes. (Alkyne metathesis is a growing area, but will not be dealt with here.) The reaction is also known as olefin disproportionation or olefin transmutation, and involves the exchange of fragments between two double bonds. Cross metathesis (CM, Figure 1) is defined as the reaction of two discrete alkene molecules to form two new alkenes. Where the two starting alkene molecules are the same it is called self-metathesis. Ethenolysis is a specific type of cross metathesis where ethylene... 

The reaction of excess amounts of methyl acrylate and the self-metathesis products of monounsaturated fatty acids like methyl ester of oleic acid with ethylene, produces valuable monomers for polycondensation polymers, as well as precursors for detergents in the presence of a suitable metathesis catalyst. In oleochemistry, azaleic and pelargonic acid were obtained industrially by ozonolysis of oleic acid. Non-linear fatty acid derivatives with two double bonds, (ricinoleic acid maleate) and one double bond (ricinoleic acid succinate) were produced from ricinoleic acid by esterification with maleic and succinic anhydride, respectively. Hydrogenation of this ricinoleic acid succinate yielded 12-hydroxystearic acid succinate which is a monomer for vegetable oil-based polyester. 

A chain mechanism for olefin metathesis explains product-time distributions in reactions between cyclo-octene and acyclic olefins. Even at the start of the reaction between cyclo-octene, trans-hut-2-ene, and trans-oct-4-ene in the presence of the catalyst, a significant amount of tetradeca-2,10-diene was found. " Tetradeca-1,9-diene was the principal product of metathesis reactions between cyclo-octene and hex-l-ene in the presence of tungsten catalysts. Ethylene and dec-5-ene formed by self-metathesis of the hex-l-ene also underwent cross-metathesis with the cyclo-octene to give deca-1,9-diene and octadeca-5,13-diene further reactions gave higher members of these homologous series. ... 

RCM usually involves the formation of a gaseous product such as ethylene. Thus the total volume of the products is more than that of the reactants, which means that the change in overall entropy is positive. Because of this, RCM too is a thermodynamically favored reaction. Unlike ROMP and RCM, cross-metathesis is a reversible reaction. Because of this, in many cross-metathesis reactions, self-metathesis and other complications may arise. 

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