Ring-opening copolymerization of CHO (cyclohexene oxide) and MA (maleic anhydride) catalyzed by the Co(III)-Salalen complex

A new complex [Co(L)(OAc)] (1), obtained from the coordination and subsequent oxidation reactions with Co(OAc)(2) and the asymmetrical Salalen ligand H2L (H2L: (E)-2-((2-3,5-di-tert-butyl-2-hydroxybenzylideneamino)phenylamino)methyl)-4,6-di-tert-butylphenol), is shown to be an effective catalyst for ring-opening copolymerization of CHO (cyclohexene oxide) and MA (maleic anhydride) in the presence of one of the three co-catalysts (DMAP (4-(dimethylamino) pyridine), TPP (triphenylphosphine) and n-Bu4NBr). 1/DMAP gives relatively higher CHO monomer conversions than that of 1/TPP or 1/n-Bu4NBr, and especially on the condition of lower temperature (50-80 degrees C), shorter reaction time (75 min) or lower catalyst feeding molar ratio (CHO:MA:1:DMAP = 500:500:1:1), all the solution polymerizations afford perfectly alternating polyester. (C) 2014 Elsevier B.V. All rights reserved.