Alkenes heterogeneously catalyzed

The stereospecific polymerization of alkenes is catalyzed by coordination compounds such as Ziegler-Natta catalysts, which are heterogeneous TiCl —AI alkyl complexes. Cobalt carbonyl is a catalyst for the polymerization of monoepoxides several rhodium and iridium coordination compounds... 

Instead ef the name metathesis, the term disproportionation is frequently applied to the reaction, and sometimes the term dismutation. For historical reasons the name disproportionation is most commonly used for the heterogeneously catalyzed reaction, while the homogeneously catalyzed reaction is usually designated as metathesis. The name disproportionation is correct in the case of the conversion of acyclic alkenes according to Eq. (1) however, this name is inadequate in most other situations, such as the reaction between two different alkenes, and reactions involving cycloalkenes. Similar objections apply to the name dismutation. The name metathesis is not subject to these limitations and, therefore, is preferred. 

Heterogeneously catalyzed hydrogenation of alkenes is generally considered to be a structure-insensitive reaction, as was deduced from numerous studies on more or less complex model catalyst systems [40-54]. However, the following sections will give examples of the opposite case. 

The first example of a heterogeneously catalyzed hydroamination of an alkene appeared in a 1929 patent in which it is claimed that NHj reacts with ethylene (450°C, 20 bar) over a reduced ammonium molybdate to give EtNH2 [24]. An intriguing reaction was also reported by Bersworth, who reacted oleic acid with NH3 in the presence of catalysts like palladium or platinum black or copper chromite to give the hydroamination product in quantitative yields [25]. However, this result could not be reproduced [26]. 

All one-step additions to C=C double bonds are mechanistically required to take place cis-selectively (ds > 99 1) (Sections 3.3.1-3.3.3). In addition, the heterogeneously catalyzed hydrogenation of alkenes also usually takes place with very high cw-selectivity, in spite of its being a multistep reaction (Section 3.3.4). 

The mechanism of the Lindlar hydrogenation is analogous to the mechanism of the heterogeneously catalyzed alkene hydrogenation (Figure 14.65). It is for this similarity... 

Homogeneous or heterogeneous catalyzed Hj reduction of unsaturated organic compounds arene, alkyne, alkene, ketone, oxime, nitrile and imine occurs readily ", e.g. ... 

The hydroformylation of alkenes is commonly run using soluble metal carbonyl complexes as catalysts but there are some reports of heterogeneously catalyzed reactions of olefins with hydrogen and carbon monoxide. Almost all of these are vapor phase reactions of ethylene or propylene with hydrogen and carbon monoxide catalyzed by rhodium, " 20 ruthenium,nickel, 22,123 cobalt, 23,124 and cobalt-molybdenum 23 catalysts as well as various sulfided metal catalysts. 23,125,126... 

The metathesis reaction of alkenes constitutes a major development in the field of hydrocarbon chemistry in recent years. The first examples of the heterogeneously and the homogeneously catalyzed metathesis of linear alkenes have been published by Banks and Bailey (I) and Calderon et al. (2), respectively. By this reaction, linear alkenes are converted with high selectivity into equimolar amounts of two new alkenes, according to ... 

The supported Co2+-substituted Wells-Dawson POM, Cs6H2[P2W17061Co(OH2)], on silica was stable up to 773 K and catalyzed the heterogeneous oxidation of various aldehydes to the corresponding carboxylic acids with 02 as a sole oxidant [116], The H5PV2Mo10O40 POM, impregnated onto meso-porous MCM-41, catalyzed the aerobic oxidation of alkanes and alkenes using isobutyraldehyde as a... 

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