Hydroformylation studies using high pressure NMR spectroscopy

Dwyer, Catherine L.; Assumption, Heidi; Coetzee, Johan; Crause, Chantelle; Damoense, Llewellyn; Kirk, Megan M.

doi:10.1016/j.ccr.2004.01.003

Cited by 40 publications

(26 citation statements)

References 29 publications

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“…As part of a continuous study [21][22][23][24] on the hydroformylation performance of different ligand classes in modified cobalt catalysis the Phoban phosphine family of ligands were also investigated systematically. In this paper, we report our results with regards to the synthesis and electronic properties of a range of these ligands as investigated through their corresponding 1 J P-Se coupling constants.…”

Section: Introductionmentioning

confidence: 99%

Steric and electronic properties in bicyclic phosphines. Crystal and molecular structures of Se=Phoban-Q (Q=C2, C3Ph, Cy and Ph)

Bungu

Otto

2007

Journal of Organometallic Chemistry

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Section: Introductionmentioning

confidence: 99%

Steric and electronic properties in bicyclic phosphines. Crystal and molecular structures of Se=Phoban-Q (Q=C2, C3Ph, Cy and Ph)

Bungu

Otto

2007

Journal of Organometallic Chemistry

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“…In scCO 2 , a substantial improvement in the selectivity for aldehydes was found by using the phosphane-containing complex in comparison to the unmodified catalyst Co 2 (CO) 8 [115]. The formation of cobalt complexes in supercritical carbon dioxide derived from Co 2 (CO) 6 [P(p-CF 3 C 6 H 4 ) 3 ] 2 under hydroformylation conditions has been investigated by in situ high-pressure NMR spectroscopy. It was found that the phosphane-modified catalyst system is stable under low carbon monoxide pressures and the hydroformylation reactions can be carried out at low pressures.…”

Section: Hydroformylation In Supercritical Fluidsmentioning

confidence: 99%

“…It was found that the phosphane-modified catalyst system is stable under low carbon monoxide pressures and the hydroformylation reactions can be carried out at low pressures. 31 P and 59 Co NMR spectra of the solution show that HCo(CO) 3 [P(p-CF 3 C 6 H 4 ) 3 ] and HCo(CO) 2 [P(p-CF 3 C 6 H 4 ) 3 ] 2 are the only hydrido cobalt complexes present in detectable concentrations in Co 2 (CO) 6 [P(p-CF 3 C 6 H 4 ) 3 ] 2catalyzed hydroformylation reactions [116].…”

Section: Hydroformylation In Supercritical Fluidsmentioning

confidence: 99%

“…Another example of synthesis taking place with very similar mechanism is hydroesterification (also termed hydroalkoxycarbonylation) that uses alcohol as hydrogen source, yielding esters as products ( The phosphane-modified cobalt-catalyzed hydroformylation of 1-dodecene was investigated using 1 and 2 as the modifier. The composition of the cobalt species in the reaction mixture was deduced from high-pressure IR and NMR spectra [6]. The modified cobalt-catalyzed 1-octene hydroformylation using phosphanes derived from limonene was investigated at 170 C and 85 bar H 2 : CO ¼ 2 : 1.…”

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confidence: 99%

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Carbonylation of Alkenes and Dienes

Kégl

2008

Modern Carbonylation Methods

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In the beginning, only cobalt catalysts were utilized for hydroformylation under relatively vigorous conditions. The moderate selectivity of the generally more desired linear isomers, the substantial formation of by-products, and the low stability of the catalysts forced more appropriate catalytic systems to be developed. Using donor ligands such as phosphanes resulted in an increase in the linear selectivity. Rhodium-containing catalysts, however, permitted the use of much milder conditions in combination with suitable ligands. Other transition metals such as ruthenium, palladium, platinum, and iridium also tended to show activity for hydroformylation, albeit a vast majority of works on hydroformylation still concentrated on rhodium-containing systems. Cobalt CatalystsThe initial rate of Co 2 (CO) 8 -catalyzed cyclohexene hydroformylation, triethyl orthoformate carbonylation, and CoH(CO) 4 formation from Co 2 (CO) 8 and H 2 is reduced by the addition of dinitrogen, argon, or xenon. It is assumed that the additional gas competes with one or more reactants for a coordinatively unsaturated site responsible for their activation, thus affecting the reaction rate [1].The carbonylation reaction of propylene oxide in the presence of various [Lewis acid] þ [Co(CO) 4 ] À salts was investigated using in situ attenuated total reflection infrared (ATR-IR) spectroscopy. b-Alkoxy-acyl-cobalttetracarbonyl species were found to be key intermediates from which two reaction routes start depending on the applied Lewis acid. Labile Lewis acid-alkoxy combinations primarily favor the production of lactone products [2].The reaction of olefins (1-octene, 3,3-dimethylbutene, cyclohexene) introduced into a preequilibrated Co 2 (CO) 8 þ H 2 system was investigated by high-pressure infrared spectroscopy. Based on the observed induction period for the formation of the corresponding aldehyde, the decrease in HCo(CO) 4 concentration and increase in Co 2 (CO) 8 concentration during the induction period, the active catalytic species of the type H x Co y (CO) z was proposed [3]. Experiments with isotope mixtures of H 2 /D 2 in the gas phase during the various steps of the reaction showed that the ratio of H/D isotopes in the hydrocarbon portion of the aldehyde product correlates with the HCo(CO) 4 /DCo(CO) 4 ratio in solution, whereas the RC(¼O)H/RC(¼O)D product ratio correlates with the H 2 /D 2 in the gas phase. It was concluded that the dominant pathway for the hydrogenolysis step in this type of hydroformylation is the direct reaction of hydrogen or deuterium with the acyl complex intermediate [4].The effect of argon (280 bar) on the rate of aldehyde formation in 1-hexene hydroformylation catalyzed by Co 2 (CO) 8 at 50 C, 70 bar P(CO) and 85 bar P(H 2 ) in toluene was investigated by high-pressure FT-IR spectroscopy. The initial rate of the reaction was found to be reduced by the presence of argon. A similar effect was observed in the RhH(CO)(PPh 3 ) 3 -catalyzed cyclohexene hydroformylation reaction [5]. 162j 7 Carbonylation of Alkenes and D...

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“…In contrast, capabilities of pressure-control during NMR data acquisition are not commercially available and have remained nonstandard. However, a significant body of research on liquid systems under pressure up to several kilobars using self-developed high-pressure NMR probes and techniques exists in the literature, and the interested reader is referred to the reviews provided in references (Dwyer et al, 2004;Winter, 2003;Sprengers et al, 2002;Yonker and Hoffmann, 2002).…”

Section: Introductionmentioning

confidence: 98%

Nuclear Magnetic Resonance: Basic Principles and Liquid State Spectroscopy

Hoffmann

2012

Characterization of Materials

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Thermogravimetric analysis (TGA) is an analytical technique for measuring changes in the mass of a material that occur in response to programmed temperature changes. The changes in the mass can be caused by a variety processes such as decomposition, degradation, sublimation, vaporization, adsorption, desorption, oxidation, and reduction. The article explains the principles of TGA and practical aspects of the method that include description of the apparatus, discussion of experimental variables, and applications. Among practical applications, a particular attention is paid to determining composition and thermal stability of materials, evaluating the kinetics of thermally stimulated processes, predicting lifetimes, and studying reactions of materials with gases. The article also addresses the issues of sample preparation as well as of basic analysis and interpretation of data. A special consideration is given to the sources of errors in the mass and temperature measurements as well as to the methods of calibrating both values.

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Hydroformylation studies using high pressure NMR spectroscopy

Cited by 40 publications

References 29 publications

Steric and electronic properties in bicyclic phosphines. Crystal and molecular structures of Se=Phoban-Q (Q=C2, C3Ph, Cy and Ph)

Steric and electronic properties in bicyclic phosphines. Crystal and molecular structures of Se=Phoban-Q (Q=C2, C3Ph, Cy and Ph)

Carbonylation of Alkenes and Dienes

Nuclear Magnetic Resonance: Basic Principles and Liquid State Spectroscopy

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