(A) study on the olefin polymerization over Pd and Ni catalysts

Abstract

Olefin polymerization was performed to study the methodologies involved in the preparation of palladium, nickel catalyst systems and the nature of the corresponding active sites involved in olefin polymerization. The influence of the modification of late transition metal complexes and reaction parameters on catalytic performances and on the final polymer properties was also examined.

Copolymerization of ethylene and carbon monoxide over (dppp)Pd${(OAc)}_2$/anion complexes (dppp = 1,3-bis(diphenylphosphino)propa-ne, anion = p-TSOH, $CF_3 CO_2 H$, $C_6 F_5 CO_2 H$, and (P$h_3$C)[B($C_6 F_5$)$_4$]) was carried out to investigate their catalytic behaviors and the properties of the polymer obtained. The catalytic activity in a protic solvent (methanol) was found to be higher than in an aprotic solvent (acetone). When p-TSOH was used as an anion, the molecular weight and melting temperature of polymer as well as the catalytic activity could be controlled with an appropriate combination of methanol and acetone instead of either methanol or acetone. Catalytic activity decreased due to steric hindrance of alcohol in the order, MeOH > i-BuOH > t-BuOH. Polymer properties such as molecular weight, melting temperature and crystalline structure were affected by the presence of water. Catalytic activity increased with water possibly because increased concentration of a hydride species may easily initiate the insertion of the olefin into a Pd-H bond via a water gas shift reaction.

Alternating copolymerization of ethylene and carbon monoxide was carried out by using the solvated cationic Pd(II) complexes, [(dppp)Pd${(S)}_2$]${[X]}_2$ (dppp = 1,3-bis(diphenylphosphino)propane, S = $CH_3 CN$, HCON($CH_3$)$_2$, $C_2 H_5 CN$, and X = $BF_4$, $ClO_4$). In addition to the use of acetonitrile, N,N-dimethylformamide and propionitrile were also used as synthesis solvent in the weakly solvated cationic palladium complexes. The activity of a catalyst with a relatively strong-coo...