24-10-2013 дата публикации
Номер: US20130281653A1
This invention is reporting new N-heterocyclic carbene based zirconium (or hafnium) complexes and their uses as catalysts for the lactones ring opening polymerization. These new catalysts are robust and versatile and exert control over polymer molecular weight and/or stereochemistry and exhibit high reactivity (cf. for low temperature applications). In particular the new catalysts show both enhanced activity and at the same time a better selectivity than the catalysts employed by the prior art. 2. A N-heterocyclic carbene according to claim 1 , whereinM is Zr,{'sub': 3', '4, 'R1 is Cl, Br, C-Calkoxy or aryloxy,'}R2 is optional and is a coordinative solvent,{'sub': 3', '4', '4', '5, 'X is Cl, Br, C-Calkoxy, aryloxy, benzyloxy, C-Calkyl or benzyl,'}{'sub': 3', '2', '5', '3', '7', '4', '9, 'R3 and R4 are independently from each other selected from the group consisting of hydrogen, CH, CH, CHand CH,'}{'sub': 3', '2', '5', '3', '7', '4', '9, 'R5 and R6 are independently from each other selected from the group consisting of hydrogen, CH, CH, CHand CH,'}R5 and R6 are optionally linked together to form an unsaturated or saturated 6 membered ring, when saturated, this cycle optionally has two chiral centers.{'sub': 1', '10', '5', '10, 'R7 and R8 are independently from each other selected from the group consisting of C-Calkyl, and C-Ccycloalkyl.'}4. A process according to claim 3 , wherein the solvent is selected from the group consisting of C-Calcohols claim 3 , dialkyletheroxides claim 3 , alkylnitriles claim 3 , aromatics claim 3 , dimethylformamide claim 3 , N-methylpyrolidone and mixtures thereof.5. A N-heterocyclic carbine according to claim 1 , wherein the coordinative solvent is tetrahydrofurane claim 1 , diethylether claim 1 , water claim 1 , acetonitrile or dimethylamine.6. A N-heterocyclic carbine according to claim 1 , wherein the X is Cl claim 1 , Br claim 1 , F or I.7. A N-heterocyclic carbine according to claim 1 , wherein at least one of R3 and R4 is ...
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