Terpolymers of N-vinylpyrrolidinone and 1-vinylimidazole as new supports for palladium nanocluster catalysts

Abstract

Two terpolymers of styrene, divinylbenzene, and 1-vinylimidazole (S/DVB/VI) or N-vinylpyrrolidinone (S/DVB/NVP) were prepared by radical polymerization. Palladium nanoparticle catalyst has been "heterogenized" by anchoring to these polymers the [PdCl 2 (PhCN) 2 ] complex via ligand exchange reaction. The formation of coordination bond between S/DVB/VI, S/DVB/NVP terpolymers and Pd 2+ ions was studied using infrared and XPS. Immobilized palladium complex was reduced during hydrogenation reaction or by reaction with sodium borohydride. Characterization of polymer supports and palladium catalysts has involved the measurements of the structural parameters in the dry state by the nitrogen BET adsorption, X-ray photoelectron spectroscopy (XPS), AAS spectroscopy and time-of-flight secondary ion mass spectrometry (TOF-SIMS). Both the catalytic systems were found efficient in the hydrogenation of cinnamaldehyde. The stability and a good recycling efficiency of these catalysts make them useful for prolonged use. The factors influencing selectivity of supported catalysts were discussed. The results offer the possibility of using these terpolymers for the immobilization of metal complex catalysts for hydrogenation and other catalytic reactions.

Rhodium(I) complex catalyst immobilized on terpolymers of N‐vinylpyrrolidinone and 1‐vinylimidazole

“…The S : DVB : VI and S : DVB : NVP molar ratios were 2 : 1 : 1 and 2 : 1 : 0.5, respectively. Details of the materials and the synthetic procedure have already been described 5…”

“…Recently we have focused our attention on using a two novel microporous functional resins as supports for palladium nanocluster catalyst. These supports were prepared by copolymerization of styrene and divinylbenzene with N ‐vinylpyrrolidinone and 1‐vinylimidazole monomers 5. Because of their chemical structure, vinylpyrrolidinone and 1‐vinylimidazole polymers form complexes with numerous low molecular weight compounds as well as with many polymers.…”

Hydrogenation of cinnamaldehyde over supported palladium catalysts

“…The steric effect exerted by the phenyl group prevents the close approach of the C=C to the surface of large particles so the molecule is tilted with C=O closer to Unauthenticated Download Date | 5/10/18 5:54 AM the surface and therefore more easily activated. This barrier does not exist by the approach of phenyl group to a small particle, therefore the selectivity to CALC of the not reduced catalyst EP5/142-Pd(II) is low 14 . The presence of the palladium nanocluster were confi rmed by XPS spectroscopy (Table 3).…”

A hybrid polyketone–SiO2 support for palladium catalysts and their applications in cinnamaldehyde hydrogenation and in 1-phenylethanol oxidation

“…On the contrary, the application of polymers as supports has been investigated to a lower extent, due to many disadvantages, such as decrease in thermal, mechanical and chemical stability, shrinking phenomena, changes of volume and porosity that can adversely influence their overall performances [5][6][7][8]. Recently, PKs, being high temperature melting materials, insoluble in the most common solvents, have been successfully proposed by us as support for palladium catalysts [9].…”