Patent ID: 7304172

Claim:
A method for preparing a copolymer of C 2 -C 10 alkylene oxide and CO 2 , with less than 10% cyclic alkylene carbonate by-product, comprising the step of reacting a C 2 -C 10 alkylene oxide and CO 2 at a CO 2 pressure ranging from 1 to 1,000 psi and a reaction temperature of 0 to 150° C. and a time of 0.1 to 50 hours in the presence of a catalyst at an alkylene oxide to catalyst ratio on a cobalt basis ranging from 200:1 to 100,000:1, said catalyst having the structure where R 1 is a hydrocarbon bridge which may be substituted with C 1 -C 20 alkyl, C 1 -C 20 alkoxy, halogen, nitro, cyano or amine; where R 2 , R 3 and R 4 can be the same or different and are selected from the group consisting of H, C 1 -C 20 alkyl, C 6 -C 20 aryl, and C 1 -C 20 fluorocarbon and where R 1 and R 2 or R 2 and R 3 or R 3 and R 4 can form a phenyl ring which can substituted with H, C 1 -C 20 alkyl, C 6 -C 20 aryl, C 1 -C 20 alkyl C 6 -C 20 aryl substituted with C 1 -C 20 alkyl, C 1 -C 20 alkoxy, phenoxy, C 1 -C 20 carboxylate, C 1 -C 20 acyl, amino, C 1 -C 20 fluoroalkyl, cyano, nitro and halogen (e.g., Cl, Br, I); and where X is any nucleophile which can ring open an epoxide; with the proviso that when X is Br and R 1 is ethyl and R 3 and R 4 form a phenyl ring, the substituent on the phenyl ring on the carbons which are not part of another ring are not all H; and when X is Br and R 1 is 1,2-cyclohexanediyl, and R 3 and R 4 form a phenyl ring, the substituent on carbon on the phenyl ring which is not part of another ring and is closest to —O— is not H; with the further proviso that X is not O 2 CCCl 3 or a nitrophenol when R 1 is 1,2-cyclohexanediyl.