Activation of molecular hydrogen in cobalt-catalyzed hydroformylation
| Autor: | Arpad Major, Felix Spindler, Rina Tannenbaum, Istaván, Piero Pino, György Bor, T. Horváth |
|---|---|
| Rok vydání: | 1991 |
| Předmět: |
chemistry.chemical_classification
Olefin fiber Reaction mechanism Organic Chemistry chemistry.chemical_element Photochemistry Biochemistry Aldehyde Catalysis Inorganic Chemistry chemistry.chemical_compound Reaction rate constant chemistry Polymer chemistry Materials Chemistry Physical and Theoretical Chemistry Cobalt Hydroformylation Carbon monoxide |
| Zdroj: | Journal of Organometallic Chemistry. 417:65-76 |
| ISSN: | 0022-328X |
| DOI: | 10.1016/0022-328x(91)80161-c |
| Popis: | The mechanism of the activation of molecular hydrogen in cobalt-catalyzed hydroformylation of olefins has been studied by high pressure IR spectroscopy using HCo(CO)4 (1) under 100 bar H2 (or D2) in the absence or presence of CO at room temperature. The treatment of 1 with 100 bar H2 resulted in the formation of CO2(CO)8 (2) and a small amount of Co4(CO)12 (3), and the transient formation of HCo3(CO)9 (4). In the reaction of 1 with one equivalent of 3,3-dimethyl-butene-1 under 100 bar H2 both hydrogenation and hydroformylation occur, but the former is much faster. In the presence of large amounts of 1 the predominant path for the hydrogenation of the olefin involves the reaction of two equivalents of 1 with the olefin even under 100 bar of H2. Under a very low partial pressure of CO the stability of 1 is increased and the hydrogenation significantly slowed down. The preferred path of the hydroformylation of the olefin involves the addition of H2 and CO from gas phase even in the presence of large amount of HCo(CO)4 (1) under 100 bar H2 and 2.3 bar COat room temperature. The studies reveal that the mechanism of H2 activation in the presence of HCo(CO)4 (1) is highly dependent on the reaction conditions. Under 100 bar H2 and at room temperature the activation of molecular hydrogen starts at a coordinatively unsaturated acyl cobalt carbonyl, yielding an aldehyde and an unknown cobalt species. It is believed that this species is a coordinatively unsaturated hydrido cobalt carbonyl like {HCo(Co)3}, and can activate and catalytically hydroformylate the olefin. |
| Databáze: | OpenAIRE |
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