Hydroformylation catalyst-binding ligands

Several modifications of the water-soluble catalysts using co-solvents (cf. Section 4.3 and [14]), micelle forming reagents (Section 4.5 and [15]), super-critical C02-water biphasic system (cf. Section 7.4 and [16]), SAPC (Section 4.7 and [17]), and catalyst binding ligands (interfacial catalysis) [18, 24] have been proposed to overcome the lower rates observed in biphasic catalysis due to poor solubilites of reactants in water. So far endeavors were centered on innovating novel catalyst and development of the existing systems. However, limited information is available on the kinetics of biphasic hydroformylation. 

In a report Chaudhari et al. [18] have shown that the rate of biphasic hydroformylation can be enhanced severalfold by using a catalyst binding ligand which facili-... 

Fig. 10 Effect of catalyst binding ligand on the rate of hydroformylation of 1-octene [18].

This concept has also been demonstrated in reverse for the hydroformylation of a water-soluble olefin (aUyl alcohol) with the organic phase containing a catalyst, H Rh (CO) (P Ph3)3. In this case, the catalyst is present in the organic phase, whereas the catalyst-binding ligand (TPPTS) is added to the aqueous phase. 

Phosphines. Polymeric phosphines exhibit strong metal-binding properties. Nonpolymeric phosphines, in particular triphenylphosphine, are employed as ligands for cobalt and rhodium in hydroformylation catalysts used in plasticizer manufacture. Extensive efforts have been made to attach phosphine-metal complexes to polymers in order to facilitate catalyst recovery and enhance selectivity... 

The supramolecular binding motifs described here were also used to attach catalysts to solid (silica) supports (128). The active metal complex could be switched from palladium to rhodium by using a polar solvent that breaks up the binding of the supramolecular motif. Allylic alkylation and hydroformylation catalysis could be carried out by using the same support "receptor" material and different "guest" ligands for the two metals a... 

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