Knowledge Bank

A series of porphyrin metal(III) compounds of general formula LMX (where L = tetraphenylporphyrin, tetrakispentafluorophenylporphyrin and octaethylporphyrin, M = Al, Cr, Co, and X = Cl- and OEt) has been synthesized and studied as catalysts for the ring opening polymerization of propylene oxide (PO) as well as copolymerization of PO with CO2 to produce polypropylene oxide (PPO), polypropylene carbonate (PPC) and propylene carbonate (PC), respectively. The electronic nature of the porphyrin ligand and the addition of Lewis basic cocatalysts e.g. DMAP and PPN+Cl- showed a dramatic influence on the catalytic TOF, product selectivity and polymeric microstructure. The origin of these effects was attributed to the electronic factors associated with the individual reaction steps and equilibriums.