Dinuclear Zinc Salen Catalysts for the Ring Opening Copolymerization of Epoxides and Carbon Dioxide or Anhydrides

摘要

A series of four dizinc complexes coordinated by salen or salan ligands, derived from ortho-vanillin and bearing (+/-)-trans-1,2-diarninocyclohexane (L-1) or 2,2-climethyl-1,3-pro-panediamine (L-2) backbones, is repotted. The complexes are characterized using a combination of X-ray crystallography, rnultinudear NMR, DOSY, and MALDI-TOF Spectroscopies, and elemental analysis. The stability of the- dinudeat complexes depends on the ligand structure) with the most stable complexes having imine substituents. The complexes are tested as catalysts for the ring-opening copolymerization (ROCOP) of CO2/cyclohexene oxide (CHO) and phthalie anhydride (PA)/CHO. All complexes are active, and the structure/activity relationships reveal that the complex having both L-2 and imine substituents displays the highest activity. In the ROCOP of CO2/CHO its activity is equivalent to other metal salen catalysts (TOP = 44 h(-1) at a catalyst loading of 0.1 mol %, 30 bar of CO2, and 80 degrees C), while for the ROCOP of PA/CHO, its activity is slightly higher than other metal salen catalysts (TOP = 198 h(-1) at a catalyst loading of 1 mol % and 100 degrees C). Poly(ester-block-carbonate) polymers are also afforded using the most active catalyst by the one-pot terpolymerization of PA/CHO/CO2.