Calixarenes modified catalysts

In Wacker oxidation, palladium complexes with sulfocalixarenes modified with nitrile-containing groups were more active than unmodified sulfocalixarenes. It has been shown that the activity of the catalysts in alkene oxidation from hexene to decene depends on the calixarene cavity size calix[4]arene is most active in the reaction with 1-hexene and calix[6]arene is most active in 1-octene oxidation [215]. 

A phosphite-modified calixarene with unsubstituted hydroxyl groups was used as a ligand in 1-hexene hydroformylation catalyzed by rhodium complexes [224], The reaction was carried out at a synthesis gas pressure of 6.0 MPa and 160 °C. Rh(acac)(CO)2 was a catalyst precursor. In 3 h, the conversion of the initial alkene virtually reached its theoretically predicted value the yield of aldehydes was 80-85%, and the normal-to-isomeric aldehyde ratio was approximately 1 1. Some similar phosphites 83 were also studied as components of catalytic systems for 1-octene hydroformylation [225]. It was shown that the nature and steric volume of substituent R have no essential effect on the main laws of the process. For example, the conversion was 80-90% at a selectivity with respect to nonanal of about 60% in all cases. The regioselectivity with respect to nonanal was considerably increased to 90-92% by using the chelate biphosphite 84 [220]. 

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