Ruthenium hydrocarbonyls

Effect of Catalyst Composition. Where acetic is the typical acid substrate, effective ruthenium catalyst precursors include ruthenium(IV) oxide, hydrate, ruthenium(III) acetyl-acetonate, triruthenium dodecacarbonyl, as well as ruthenium hydrocarbonyls, in combination with iodide-containing promoters like HI and alkyl iodides. Highest yields of these higher MW acids are achieved with the Ru02-Mel combination,... 

Ruthenium complexes have been used in the hydrocarbonylation of simple esters to produce the corresponding homologous esters (50). The hydrocarbonylation affects the alkyl moiety rather than the carboxylate group ... 

The cobalt is present as a carbonyl derivative and can be directly active in the hydrocarbonylation steps of the process only when a large excess of cobalt is used in the presence of phosphine ligands and iodide promoters (Co/Ru 10/1). In this case the ruthenium is probably mainly involved in the hydrogenation of the aldehydes and their acetals to alcohols (O. 

Pretzer et al. have investigated the hydrogenation potential of different noble metal acetylacetonates in the cobalKatalyzed methanol hydrocarbonylation (c.f. Table VIII). The best results have been obtained with ruthenium, followed by rhodium. In an optimized system of that type, it was possible to achieve 80% molar selectivity to ethanol at a 30% conversion of methanol. Interestingly, the addition of platinum resulted in an increase of acetaldehyde selectivity (20]. 

The addition of increasing amounts of iodine promoters accelerates the hydrocarbonylation of methanol, but at the same time detioriates the hydrogenation ability of the cobalt catalysis. To obtain a high ethanol selectivity under these conditions, catalysts active for hydrogenation in the presence of iodine have to be added. Ruthenium compounds have been proved to be most suitable, as was mentioned earlier. Althou no detailed studies on the ruthenium intermediates involved are available, it is well known that aliphatic aldehydes... 

Besides hydrocarbonylation of olefins with carbon monoxide, hydroacylation can also be achieved by addition of aldehydes to olefins in the absence of carbon monoxide. This reaction is usually induced by rhodium complexes, mainly of the Wilkinson s catalyst type. Other catalysts are also active, e.g., systems derived from ruthenium complexes. Hydroacylation via aldehyde addition reactions has only rarely been surveyed24. 

Als Katalysatoren eignen sich eine Vielzahl von Ubergangsmetallen. Besondere Bedeutunghaben Nickel, (Cobalt, Rhodium, Palladium, Platin und Eisen. Kupl er, Ruthenium, Osmium und Manganfinden ebenfalls Anwendung. Die eigentlich katalytisch wirksamen Spezies sind Carbonyl- oder Hydrocarbonyl-Komplexe dieser Metalle. 

Jeimer G (1988) Hydrocarbonylation of linear and branched aliphatic C2-C4 alcohols catalyzed by cobalt-ruthenium systems. A comparative study. J Organomet Chem 346(2) 237-251... 

The catalytic hydrocarbonylation and hydrocarboxylation of olefins, alkynes, and other TT-bonded compounds are reactions of important industrial potential.Various transition metal complexes, such as palladium, rhodium, ruthenium, or nickel complexes, have widely been used in combination with phosphines and other types of ligands as catalysts in most carbonylation reactions. The reactions of alkenes, alkynes, and other related substrates with carbon monoxide in the presence of group VIII metals and a source of proton affords various carboxylic acids or carboxylic acid derivatives.f f f f f While many metals have successfully been employed as catalysts in these reactions, they often lead to mixtures of products under drastic experimental conditions.f i f f f In the last twenty years, palladium complexes are the most frequently and successfully used catalysts for regio-, stereo-, and enantioselective hydrocarbonylation and hydrocarboxylation reactions.f ... 

When formaldehyde reacts with rhodium halides, carbonylation proceeds (hydrocarbonylation between formaldehyde and a ruthenium halide as described in Chapter 16 proceeds). A Vaska type rhodium complex is obtained by the reaction with phosphine as shown in eq. (18.7) [17]. 

Active catalysts are nickel, cobalt, iron, rhodium, ruthenium and palladium, as well as their salts, carbonyls or hydrocarbonyls. 

More recently, systems based on polypyridine coordination compounds of ruthenium(II) [46-49], rhodium(I) [50a] and iridium(I) [50] have been shown to efficiently catalyse the thermal WGSR. An important effect of the substituent ortho to the nitrogen atom of the ligand has been demonstrated in the case of Ir(I) leading to one of the most efficient catalysts known today [50b]. [Ru(bpy)2(CO)Cl] has also been studied and all of the possible intermediates within the catalytic cycle (hydrocarbonyl complex, metal hydride, aquo species) have been isolated and characterized [48]. 

---