Studies on new palladium(II) catalyst system for copolymerization of CO with ethylene

In this paper, a new class of four-membered catalyst system, PdCl2/MA(n)/DP PP1/CF3COOH, was firstly studied for copolymerization of CO with ethylene t o prepare linear alternating polyketone, in which MA(n) component was mainl y studied. The experimental results showed that this kind of new catalyst s ystem exhibited highly efficient activity; especially when Cd(OAc)(2). 2H(2 )O, Zn(OAc)(2). 4H(2)O, Fe(ClO4)(3). 9H(2)O, Pb(OAc)(2). 3H(2)O and Cu(OAc) (2).H2O were used as MA(n) component, the corresponding catalyst system had very highly efficient activity of 8100, 7100, 6000, 6000 and 5800 g polyke tone/(g Pd h), respectively under conditions of 6.5 MPa and 110 degreesC. T he effects of MA(n) component were also investigated; the results showed th at suitable MA(n) was probably a metal compound of weakly coordinating anio ns; Mn+ probably coordinated with Cl- more strongly than palladium(II); the stability of chelate complex (c) of Mn+ with DPPP was probably between mon o-chelate ring and bis-chelate ring complexes of palladium(II) with DPPP. T his new highly efficient catalyst system had the advantages of having high stability and low cost. (C) 2001 Elsevier Science B.V. All rights reserved.