Abstract
A new three-component catalytic system, PdCl2/phen/M(CF3SO3)n where M = La, Y, Yb, Zn, and Cu, was studied for the copolymerization of norbornene (NBE) with CO to prepare polyketone (PK). It was found that the CF3SO3H catalytic system gave a low catalytic activity for the copolymerization of norbornene with CO, but when M(CF3SO3)n was introduced instead of CF3SO3H, the PdCl2/phen/M(CF3SO3)n catalytic system exhibited much higher activity. The effects of ligands, M(CF3SO3)n, solvents, and temperatures on the copolymerization have been discussed in detail. The results showed that with 1,10-phenanthroline (phen) and Cu(CF3SO3)2 used as cocatalysts, the corresponding reaction rate reached 82 000 g PK (mol Pd)−1h−1 when the reaction was carried out in methanol at 90°C and 3.0 MPa of CO, and the weight average molecular weight (M w) of the resultant copolymer is 1090 g/mol. The copolymer was characterized with various techniques such as FT-IR, 1HNMR, 13CNMR, TGA, and DSC. The infrared spectrum of the product includes two features at 1697 and 1732 cm−1 for the NBE/CO copolymer in CH3OH that are attributed to carbonyl groups in ketones (repeating unit) and esters (end group), respectively. Due to the tension of the ring of norbornene, the degree of copolymerization is not high.
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