Polycarbonates made using highly selective catalysts
AssigneeCornell Research Foundation, Inc.
InventorsGeoffrey W. Coates, Zengquan Qin, Claire Tova Cohen
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Abstract
Poly(propylene carbonates) are prepared from propylene oxide and CO2 with less than 10% cyclic propylene carbonate by product using cobalt based catalysts of structure preferably in combination with salt cocatalyst, very preferably cocatalyst where the cation is PPN+ and the anion is Cl− or OBzF5−. Novel products include poly(propylene carbonates) having a stereoregularity greater than 90% and/or a regioregularity of greater than 90%.
Claims7
A method for preparing a copolymer of C2-C10 alkylene oxide and CO2, with less than 10% cyclic alkylene carbonate by-product, comprising the step of reacting a C2-C10 alkylene oxide and CO2 at a CO2 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 R1 is a hydrocarbon bridge which may be substituted with C1-C20 alkyl, C1-C20 alkoxy, halogen, nitro, cyano or amine;
- where R2, R3 and R4 can be the same or different and are selected from the group consisting of H, C1-C20 alkyl, C6-C20 aryl, and C1-C20 fluorocarbon and where R1 and R2 or R2 and R3 or R3 and R4 can form a phenyl ring which can substituted with H, C1-C20 alkyl, C6-C20 aryl, C1-C20 alkyl C6-C20 aryl substituted with C1-C20 alkyl, C1-C20 alkoxy, phenoxy, C1-C20 carboxylate, C1-C20 acyl, amino, C1-C20 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 R1 is ethyl and R3 and R4 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 R1 is 1,2-cyclohexanediyl, and R3 and R4 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 O2CCCl3 or a nitrophenol when R1 is 1,2-cyclohexanediyl.
A method for preparing poly(C2-C10 alkylene carbonate, with less than 10% cyclic alkylene carbonate by-product, comprising the step of reacting C2-C10 alkylene oxide, e.g., propylene oxide, and CO2 at a CO2 pressure ranging from 10 psi to 300 psi, a reaction temperature of 20 to 25° C., a reaction time of 0.5 to 10 hours in the presence of the catalyst system for epoxide/CO2 copolymerization comprising as a catalyst
- R1 is a hydrocarbon bridge which may be substituted with C1-C20 alkyl, C1-C20 alkoxy, halogen (e.g., Cl, Br, I), nitro, cyano or amine;
- where R2, R3 and R4 can be the same or different and are selected from the group consisting of H, C1-C20 alkyl, C6-C20 aryl, and C1-C20 fluorocarbon and where R1 and R2 or R2 and R3 or R3 and R4 can form a phenyl ring which can substituted with H, C1-C20 alkyl, C6-C20 aryl, C1-C20 alkyl C6-C20 aryl substituted with C1-C20 alkyl, C1-C20 alkoxy, phenoxy, C1-C20 carboxylate, C1-C20 acyl, amino, C1-C20 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 R1 is ethyl and R3 and R4 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 R1 is 1,2-cyclohexanediyl, and R3 and R4 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 O2CCCl3 or a nitrophenol when R1 is 1,2-cyclohexanediyl, and as a cocatalyst a salt which is bulky and non-coordinating where the cation is a phosphorus and/or nitrogen based cation of at least 50 g/mol, e.g., selected from the group consisting of [R4N]+, [R4P]+, [R3P═N═PR3]+ and [P(NR3)3]3+ where R is C1-C20 alkyl, C6-C20 aryl, C6-C20 alkoxy or a solid support and the anion is a nucleophile which can ring open an epoxide and the R groups can be the same or different.
- where the ratio of alkylene oxide to cocatalyst to catalyst ranges from 500-100,000:0.5-1.5:0.5-1.5.
Dependencies are inferred from the claim text.