Effect of Phosphines on the Thermodynamics of the Cobalt-Catalyzed Hydroformylation System
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- 作者：Robert J. Klingler ; Michael J. Chen ; Jerome W. Rathke ; Kurt W. Kramarz
- 刊名：Organometallics
- 出版年：2007
- 出版时间：January 15, 2007
- 年：2007
- 卷：26
- 期：2
- 页码：352 - 357
- 全文大小：75K
- 年卷期：v.26,no.2(January 15, 2007)
- ISSN：1520-6041
文摘
Thermodynamic parameters relevant to the phosphine-modified cobalt hydroformylation reaction arereported. Equilibrium constants for the hydrogenation of Co2(CO)6L2 to yield HCo(CO)3L were determinedusing in situ 1H and 31P NMR spectroscopy between 75 and 175 
C for various solvents and phosphineligands. Special emphasis was placed on n-Bu3P, as this ligand is prototypical of the Shell hydroformylationprocess. The resultant van't Hoff plots yield the enthalpy and entropy change (
H = 7.0 ± 0.4 kcal/moland S = 2 ± 1 cal/mol·K) for the case of L = n-Bu3P in benzene solvent. These parameters were foundto be relatively insensitive to changes in the solvent, suggesting that the hydride product is not verypolar. Even for isobutyl alcohol solvent, the resultant enthalpy and entropy changes (H = 5.8 ± 0.4kcal/mol and S = -2 ± 1 cal/mol·K) were found to be similar to those obtained in benzene and dioxane.Analysis of the 31P NMR line widths allows rigorous lower limits to be established for the catalyticallyrelevant Co-Co and Co-H bond energies in the case of L = n-Bu3P (Co-Co 
23 kcal/mol and Co-H 60 kcal/mol) relative to the previously reported values for the case of L = CO (Co-Co = 19 ± 2kcal/mol and Co-H = 59 ± 1 kcal/mol).
C for various solvents and phosphineligands. Special emphasis was placed on n-Bu3P, as this ligand is prototypical of the Shell hydroformylationprocess. The resultant van't Hoff plots yield the enthalpy and entropy change (H = 7.0 ± 0.4 kcal/moland S = 2 ± 1 cal/mol·K) for the case of L = n-Bu3P in benzene solvent. These parameters were foundto be relatively insensitive to changes in the solvent, suggesting that the hydride product is not verypolar. Even for isobutyl alcohol solvent, the resultant enthalpy and entropy changes (H = 5.8 ± 0.4kcal/mol and S = -2 ± 1 cal/mol·K) were found to be similar to those obtained in benzene and dioxane.Analysis of the 31P NMR line widths allows rigorous lower limits to be established for the catalyticallyrelevant Co-Co and Co-H bond energies in the case of L = n-Bu3P (Co-Co 23 kcal/mol and Co-H 60 kcal/mol) relative to the previously reported values for the case of L = CO (Co-Co = 19 ± 2kcal/mol and Co-H = 59 ± 1 kcal/mol).