Phosphine ligands hydroformylation

Table 5.2-1 Comparison of different phosphine ligands in the Rh-catalyzed hydroformylation of 1-octene in [BMIM][PFd.

Cationic phosphine ligands containing guanidiniumphenyl moieties were originally developed in order to make use of their pronounced solubility in water [72, 73]. They were shown to form active catalytic systems in Pd-mediated C-C coupling reactions between aryl iodides and alkynes (Castro-Stephens-Sonogashira reaction) [72, 74] and Rh-catalyzed hydroformylation of olefins in aqueous two-phase systems [75]. 

When water-miscible ionic liquids are used as solvents, and when the products are partly or totally soluble in these ionic liquids, the addition of polar solvents, such as water, in a separation step after the reaction can make the ionic liquid more hydrophilic and facilitate the separation of the products from the ionic liquid/water mixture (Table 5.3-2, case e). This concept has been developed by Union Carbide for the hydroformylation of higher alkenes catalyzed by Rh-sulfonated phosphine ligand in the N-methylpyrrolidone (NMP)/water system. Thanks to the presence of NMP, the reaction is performed in one homogeneous phase. After the reaction. 

Hydroformylation of vinyl acetate to give mainly the branched product in >90% ee has been achieved using a rhodium catalyst containing binaphthol and phosphine ligands anchored to polystyrene. 

Ligand self-assembly through coordinative bonding has been used to increase the bulkiness of a monodentate tris-3-pyridyl phosphine ligand employing the zinc porphyrin/pyridine interaction (Scheme 33) [95-97]. The corresponding rhodium catalyst allowed for regioselective hydroformylation of2-octene [95]. 

After a hydroformylation run, the reaction solution was subjected to ultrafiltration using an asymmetric polyethersulfone membrane (MWCO 50 kDa) supplied by Sartorius. A retention of 99.8% was found. When the catalyst solution was recycled, virtually the same catalytic activity was observed again (165 TO h 1). Repetitive recycling experiments resulted in 2-7% loss of rhodium, which was subscribed to partial oxidation of the phosphine ligand. 

Takaya and co-workers in 1993 were the first to report on asymmetric hydroformylation using phosphite-phosphine ligands [59]. In an attempt to combine the effectiveness of the BINOL chemistry for asymmetric catalysis and the effectiveness of the phosphite moiety for asymmetric hydroformylation, they developed the (.R,S)-BINAPHOS ligand 3, which turned out to be very efficient (Fig. 6). 

The synthesis of aldehydes via hydroformylation of alkenes is an important industrial process used to produce in the region of 6 million tonnes a year of aldehydes. These compounds are used as intermediates in the manufacture of plasticizers, soaps, detergents and pharmaceutical products [7], While the majority of aldehydes prepared from alkene hydroformylation are done so in organic solvents, some research in 1975 showed that rhodium complexes with sulfonated phosphine ligands immobilized in water were able to hydroformylate propene with virtually complete retention of rhodium in the aqueous phase [8], Since catalyst loss is a major problem in the production of bulk chemicals of this nature, the process was scaled up, culminating in the Ruhrchemie-Rhone-Poulenc process for hydroformylation of propene, initially on a 120000 tonne per year scale [9], The development of this biphasic process represents one of the major transitions since the discovery of the hydroformylation reaction. The key transitions in this field include [10] ... 

Figure 11.6 Effect of varying the water soluble phosphine ligand on the hydroformylation of propene to butyraldehyde. P Rh ratio = TPPTS 80 BISBIS 7 NORBOS 14 BINAS 7...

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