Fluorous hydroformylation

Hydroformylation is an industrially important carbonylation process that is used in the synthesis of aldehydes from olefins, CO and molecular hydrogen by homogeneous catalysis. Efficient catalyst recovery is crucial for the process to be economically viable. Pioneering work in fluorous chemistry was published in 1994 by Horvdth and Rabai, who studied the fluorous hydroformylation of olefins catalyzed by an Rh complex with a fluorous phosphine as a ligand. ... 

Later work modified the conditions for the Rh-catalyzed fluorous hydroformylation of 1-octene by omitting toluene. Thus, the fluorous hydroformylation was carried out with PFMC as the sole solvent and a fluorous Rh catalyst derived from... 

The use of thermomorphic systems has recently been studied as a way of achieving catalyst separation in homogeneous catalysis. For example, a biphasic hydroformylation catalyst system was developed to take advantage of the unusual solvent characteristics of perfluorocarbons combined with typical organic solvents (4). Fluorous/organic mixtures such as perfiuoromethylcyclohexane... 

Various other biphasic solutions to the separation problem are considered in other chapters of this book, but an especially attractive alternative was introduced by Horvath and co-workers in 1994.[1] He coined the term catalysis in the fluorous biphase and the process uses the temperature dependent miscibility of fluorinated solvents (organic solvents in which most or all of the hydrogen atoms have been replaced by fluorine atoms) with normal organic solvents, to provide a possible answer to the biphasic hydroformylation of long-chain alkenes. At temperatures close to the operating temperature of many catalytic reactions (60-120°C), the fluorous and organic solvents mix, but at temperatures near ambient they phase separate cleanly. Since that time, many other reactions have been demonstrated under fluorous biphasic conditions and these form the basis of this chapter. The subject has been comprehensively reviewed, [2-6] so this chapter gives an overview and finishes with some process considerations. 

Figure 6.7. Hydroformylation of an alkene using a rhodium complex bearing a fluorous ponytail.[l, 22]...

Figure 6.10. Fluorous polymers with bound PPh3 used in the hydroformylation of l-hexene.[46]...

Process Synthesis for the Fluorous Biphasic Hydroformylation of 1-Octene... 

Figure 6.35. Schematic design of a full-scale fluorous biphasic reactor for the hydroformylation of 1-octene...

I. T. Horvath, J. R abai, Facile Catalyst Separation without Water Fluorous Biphase Hydroformylation of Olefins , Science 1994, 266, 72. 

The fluorous solvent alone had a minimal effect on the outcome of the reaction. However, with the fluorinated ligand, the rr.iso ratio was found to increase with increasing phosphine concentration, reaching a value of almost 8 1 at a phosphine to rhodium ratio of 103 1. The beauty of this system was demonstrated by its use in a semicontinuous hydroformylation experiment. After each... 

Modified cobalt complexes of the type frans-Co2(CO)6(phosphine)2 are promising candidates for certain transition metal-catalyzed reactions, in particular for the hydroformylation of long-chained olefins [117]. A series of complexes Co2(CO)6[P(alkyl) (aryl)m]2 (n 0,1,2,3 m S - n) was synthesized and used for solubility measurements. Since the basicity of phosphines affects the catalytic activity, use of fluorous substituents might induce unexpected changes in the activity. Therefore, also derivatives with an additional ethyl spacer between the fluorous group and the phosphine moiety were examined (Sect. 3.1). 

Syntheses of perfluoroalkylated Xantphos derivatives have been reported normal-sclcctiYC hydroformylation in fluorous media is anticipated to be disclosed. 

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