Rare earth metal coordination compounds as lactone polymerization catalysts
First Claim
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1. A process for polymerizing lactide comprising:
- contacting at 100°
C. to 220°
C. a lactide and up to 20 mole percent of another lactone selected from the group consisting of ##STR6## and mixtures thereof, where n is 4 or 5, h, i, k and m are independently 1 or 2, each R is independently selected from H, a hydrocarbyl containing up to 12 carbon atoms or substituted hydrocarbyl containing up to 12 carbon atoms with a catalytic amount of a catalyst of the formula MZ3, or MZ3 coordinated with one or more neutral ligands, wherein M is metal selected from the group consisting of scandium, yttrium, bismuth and lanthanide series rare earth metals and the Zs are independently the same or different highly coordinating ligands and cooling the resulting polymer.
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Abstract
A process for polymerizing lactide and up to 20 mole percent of another lactone is disclosed. The cayalysts used have the formula MZ3 wherein M is scandium, yttrium, bismuth, a lanthanide series rare earth metal or a mixture thereof and the Zs are independently the same or different highly coordinating ligands. The preferred metals M are lanthanum, cerium, praseodymium and neodymium with lanthanum being especially preferred. The preferred ligands are betadiketones, betaketoesters and malonate anions with the betadiketones such as 2,2,6,6-tetramethyl-3,5-heptanedionates being especially preferred.
23 Citations
19 Claims
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1. A process for polymerizing lactide comprising:
- contacting at 100°
C. to 220°
C. a lactide and up to 20 mole percent of another lactone selected from the group consisting of ##STR6## and mixtures thereof, where n is 4 or 5, h, i, k and m are independently 1 or 2, each R is independently selected from H, a hydrocarbyl containing up to 12 carbon atoms or substituted hydrocarbyl containing up to 12 carbon atoms with a catalytic amount of a catalyst of the formula MZ3, or MZ3 coordinated with one or more neutral ligands, wherein M is metal selected from the group consisting of scandium, yttrium, bismuth and lanthanide series rare earth metals and the Zs are independently the same or different highly coordinating ligands and cooling the resulting polymer. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19)
- contacting at 100°
Specification