CO and Olefins

The direct carbonylation of heterocycles with CO and olefins proceeds efficiently. The reaction of pyridine, CO, and 1-hexene in the presence of Ru3(CO)12 at 150 °C gives a-acylated pyridines (Equation (84)).111,llla A number of olefins including ethene and 1-eicosene can be used in this carbonylation reaction. 

CO and olefins, 11, 721 cyclic olefins, 11, 716 silicones, 3, 670 Copper catalysts... 

Transition metal carbonyls and their derivatives are remarkably effective and varied in their ability to catalyze reactions between unsaturated molecules (e.g., CO and olefinic compounds) or between certain saturated and unsaturated molecules (e.g., olefins and H2 or H20). The carbonyl derivatives of cobalt are particularly active catalysts for such reactions and have been put to use in the industrial synthesis of higher aliphatic alcohols. In fact, much of the growth in knowledge concerning catalysis by metal carbonyls has been stimulated by the industrial importance of the Fischer-Tropsch synthesis, and by the economically less important, but chemically more tractable, hydroformylation reaction. 

In addition to five- and six-membered N-heteroaromatics, other N-heterocyclic compounds have been found to serve as substrates for C-H carbonylation reactions. Benzoimidazole 13 reacted in the same way with CO and olefins in the presence of Ru3(CO)12, but carbonylation occurred at the C-H bond / to the sp2 nitrogen to give 14 (Table 1). The same relationship between reactivity and the pK, values of conjugate acids of heterocycles was also observed in the /8 carbonylation [4],... 

Besides the class of traditional phosphines ligands, the related class of phosphite ligands has been utilized as ancillary ligation in various industrially relevant processes such as the hydrocyanation see Hydrocyanation) of dienes or hydroformylation see Hydroformylation) or the copolymerization of CO and olefins.The thermochemistry of ligand substitution of a variety of phosphite ligands has... 

This reaction is considered to proceed via initial coordination of pyridine to one of ruthenium centers, after which the adjacent ruthenium cleaves the ortho C-H bond followed by successive insertion of CO and olefin. When 2-phenylpyridine is employed in a similar system, acylation in the phenyl ring takes place via prior coordination of the N atom followed by cleavage of proximal C-H bond in the phenyl group (Scheme 14.7) [19]. 

Chain propagation of CO/ethylene copolymerization proceeds by a strictly alternating insertion of CO and olefin monomers in the growing chain. It is safe to assume that double CO insertion does not occur for thermodynamic reasons [Ic]. However, the complete absence of double ethylene insertions is remarkable because ethylene insertion in a Pd-alkyl species must be exothermic by about 20 kcal/mol (84 kJ mol). The observation of strict alternation is the more surprising since the same palladium catalysts also efficiently dimerize ethylene to butenes [25]. The perfect alternation is maintained even in the presence of very low concentrations of carbon monoxide. When starting abatch polymerization at a high ethylene/CO ratio, error-free copolymer is produced until all the CO is consumed then the system starts forming butenes (with some catalyst systems at about twice the rate of copolymerization ). 

Using a related reaction. Sen showed that the palladium-catalyzed alternating copolymerization of CO and olefins could be carried out under aqueous conditions by using either the sulfonated chelating phosphine ligand, l,3-bis(diphenyl-phosphino)propane (dppp), or a sulfonated phenanthroline ligand, Phen-SO. Na (eq. (9)) [32]. 

Consistent with the finding that less flexible ligands decrease the reaction rate for carbon monoxide insertion, the rigid bidentate nitrogen ligand bis(arylimino)acenaphthene allowed the isolation and characterization of the products of successive insertion of CO and olefin (norbornadiene, NBD" ... 

The successive insertion of CO and olefin into a Pd—C bond leads to an alternating copolymerization of CO and olefins [ 100]. When the reaction is carried out with an isolated, cationic acetylpalladium catalyst, living polymerization giving a singly dispersed polymer proceeds (eq (72)) [lOI]. 

The synthesis of alternating copolymers from carbon monoxide (CO) and olefins using palladium catalysts is currently an area of intense research. In cases where a-olefins are used, the regiochemistry (head/tail orientations) and stereochemistry (tacticity) of olefin insertion have a strong influence on the physical and mechanical properties of the polymers. Unlike regioregular a-olefins homopolymers, these copolymers have a directionality along the polymer backbone due to the incorporation of CO. Therefore isotactic, regioregular CO/a-olefin polymers are chiral by virtue of their main-chain stereochemistry (Scheme 11). 

Such reactions constitute important steps in the oxidation of CO and olefins by metal ions such as Hg(II), Tl(in), and Pd(II) - . 

The synthesis of alternating copolymers from carbon monoxide (CO) and olefins using palladium catalysts is currently an area of intense research interest. In cases where a-olefins are used, the regiochemistry (head/tail orientations) and stereo-... 

Various elementary processes such as oxidative addition, reductive elimination, olefin and CO insertion into the metal-to-carbon bond have found extensive applications in organic synthesis. Other processes such as attack of nucleophiles on metal-bound CO and olefins, unique reactions of metal carbene complexes, and a-bond metatheses are among the topics of special interest to organometalhc chemists as well as to synthetic organic chemists. Our aim is to provide the reader with detailed accounts of elementary processes with the hope that the information provided here is used for further development of molecular catalysis. 

Insertion reactions play an important role in the catalysis of C-C and C-H coupling [1]. Insertion of CO and olefins into metal-alkyl and metal-hydride bonds are of major importance in industrial chemistry. Insertion reactions take place according to... 

Metals readily adsorb unsaturated molecules such as CO and olefins. If they are adsorbed irreversibly in molecular form, then they act as poisons. If dissociation or decomposition occurs, tiien this can lead to deactivation by coking. 

Au particles supported on reducible oxides such as titania or ceria are also efficient catalysts for the water-gas shift, the destruction of sulfur dioxide (DeSOx processes), the complete oxidation of methane, the selective or partial oxidation of propene, the hydrogenation of CO and olefins, and the reduction of NO with hydrocarbons. Depending on the conditions, Au/TiOs... 

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