Homogeneous rhodium catalyzed

Homogeneous rhodium-catalyzed hydroformylation (135,136) of propene to -butyraldehyde (qv) was commercialized in 1976. -Butyraldehyde is a key intermediate in the synthesis of 2-ethyIhexanol, an important plasticizer alcohol. Hydroformylation is carried out at <2 MPa (<290 psi) at 100°C. A large excess of triphenyl phosphine contributes to catalyst life and high selectivity for -butyraldehyde (>10 1) yielding few side products (137). Normally, product separation from the catalyst [Rh(P(C2H2)3)3(CO)H] [17185-29-4] is achieved by distillation. 

The procedure has been successfully tested on synthetic data and applied to the homogeneous rhodium catalyzed hydroformylation reaction, where the 2D tracks for the peak center positions of both organometallic intermediates and products were identified. If the data is collected in a very small region of composition... 

The homogeneous rhodium catalyzed hydroformylation of isoprene was the first application of SA to spectral reconstruction of a real catalytic system [92]. The MIR... 

L. Chen, The Exploratory Chemometric Studies of the Homogeneous Rhodium Catalyzed Hydroformylation of Iso-prene, PhD Thesis, National University of Singapore, 2001. 

The accessible molecular surface (AMS) model is introduced as a unique approach for the description of steric ligand effects in homogeneous rhodium-catalyzed hydrogenation of CO2 to formic acid [33]. 

The stereochemistry of the homogeneous rhodium-catalyzed alcoholysis reaction has also been studied (77) (eq. [52]). The predominant stereochemistry was established through a Walden cycle, reduction of the alkoxysilane 142 occurring with almost complete retention at silicon. As shown in Table 31, the rhodium-catalyzed alcoholysis occurs with retention of configuration but low stereoselectivity. Moreover, when the alcohol was used as solvent, predominant inversion or racemization was observed. Predominant inversion was also found in alcoholysis of a substituted silacyclopentane (171), but concomitant epimerization yielding the equilibrium mixture of isomers was observed. 

Feng J, Garland M (1999) Unmodified homogeneous rhodium-catalyzed hydroformylation of styrene. The detailed kinetics of the regioselective synthesis. Organometallics 18(3) 417-427... 

Li CZ, Chen L, Widjaja E, Garland M (2010) The catalytic binuclear elimination reaction confirmation from in situ FTIR studies of homogeneous rhodium catalyzed hydroformylation. Catal Today 155 261-265... 

A recyclable system for the directed rhodium-catalyzed hydroacylation of olefins was reported using a homogeneous phenol and 4,4 -dipyridyl solvent system at 150 °C. High yields were obtained even after eight cycles and the ketone product was obtained after decantation (Equation (132)).115... 

In 1968, Knowles et al. [1] and Horner et al. [2] independently reported the use of a chiral, enantiomerically enriched, monodentate phosphine ligand in the rhodium-catalyzed homogeneous hydrogenation of a prochiral alkene (Scheme 28.1). Although enantioselectivities were low, this demonstrated the transformation of Wilkinson s catalyst, Rh(PPh3)3Cl [3] into an enantioselective homogeneous hydrogenation catalyst [4]. 

Optically active aldehydes are important precursors for biologically active compounds, and much effort has been applied to their asymmetric synthesis. Asymmetric hydroformylation has attracted much attention as a potential route to enantiomerically pure aldehyde because this method starts from inexpensive olefins and synthesis gas (CO/H2). Although rhodium-catalyzed hydrogenation has been one of the most important applications of homogeneous catalysis in industry, rhodium-mediated hydroformylation has also been extensively studied as a route to aldehydes. 

A similar phenomenon was observed in a homogeneous rhodium complex catalyzed hydrogenation (equation 56)6. 

In 1975 Kuntz has described that the complexes formed from various rhodium-containing precursors and the sulfonated phosphines, TPPDS (2) or TPPTS (3) were active catalysts of hydroformylafion of propene and 1-hexene [15,33] in aqueous/organic biphasic systems with virtually complete retention of rhodium in the aqueous phase. The development of this fundamental discovery into a large scale industrial operation, known these days as the Ruhrchemie-Rhone Poulenc (RCH-RP) process for hydroformylation of propene, demanded intensive research efforts [21,28]. Tire final result of these is characterized by the data in Table 4.2 in comparison with cobalt- or rhodium-catalyzed processes taking place in homogeneous organic phases. 

Weis, M., Waloch, C., Seiche, W. and Breit, B. (2006) Self-assembly of bidentate ligands for combinatorial homogeneous catalysis Asymmetric rhodium-catalyzed hydrogenation. J. Am. Chem. Soc.. 128. 4188-4189. 

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