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Regio‐ and stereoregular copolymerisation of propene with carbon monoxide catalysed by palladium complexes containing atropisomeric diphosphine ligands
Author(s) -
Bronco Simona,
Consiglio Giambattista
Publication year - 1996
Publication title -
macromolecular chemistry and physics
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.57
H-Index - 112
eISSN - 1521-3935
pISSN - 1022-1352
DOI - 10.1002/macp.1996.021970127
Subject(s) - carbon monoxide , propene , palladium , chemistry , polymer chemistry , catalysis , organic chemistry
The use of palladium catalysts, modified by chelate diphosphine ligands based on a diphenyl atropisomeric moiety, permits a good control of regio‐ and stereochemistry in the alternating copolymerisation of propene with carbon monoxide. The completely aromatic ligands ( S )‐(6,6′‐dimethoxybiphenyl‐2,2′‐diyl)bis(diphenylphosphine) and ( S )‐(6,6′‐dimethylbiphenyl‐2,2′‐diyl)bis(diphenylphosphine) give regioirregular materials. Their stereoregularity cannot be easily evaluated but appears to be rather low on the basis of optical activity determinations. Using ligands containing sterically hindered alkyl substituents on the phosphorus atoms (such as cyclohexyl or isopropyl) completely regioregular copolymerisation takes place. The produce copolymers show a high degree of stereoregularity approaching 96% of l ‐diads. Ligands lacking C 2 symmetry show only a small decrease in regioregularity and stereoregularity. Very high catalytic activity is observed with the ligand ( all S )‐( R a )‐(6,6′‐dimethoxybiphenyl‐2,2′‐diyl)bis(2,5‐dimethylphospholane). This ligand allows the production of a completely regioregular copolymer that shows almost complete atacticity.