title: Discovery and optimization of new chromium catalysts for ethylene oligomerization and polymerization aided by high-throughput screening.
abstract: High throughput screening (HTS) of a 205 member Schiff base salicylaldimine ligand library derived from salicylaldehydes bearing bulky ortho-substituents, i.e., 9-anthracenyl, 1,4,5,8-tetramethylanthracenyl or triptycenyl, reacted in-situ with (p-tolyl)CrCl2(thf)3, identified two new classes of highly active chromium based systems for the oligomerization and polymerization of ethylene, respectively. The polymerization system comprises bidentate ortho-substituted anthracenyl Schiff bases bearing small primary or secondary alkyl imine substituents. The oligomerization catalysts are based upon tridentate ortho-triptycenyl-substituted Schiff bases with pyridylmethyl or quinolyl substituents. Validation tests confirmed polymerization productivities of up to 3000 g x mmol(-1)h(-1)bar(-1) for the polymerization catalyst systems while the oligomerization catalysts gave productivities up to 10 000 g x mmol(-1)h(-1)bar(-1). Key catalyst precursors have been characterized by X-ray crystallography.
authors.affiliation: Imperial College London, Exhibition Road, London SW7 2AZ, United Kingdom.
authors.forename: David J
authors.initials: DJ
authors.lastname: Jones
authors.forename: Vernon C
authors.initials: VC
authors.lastname: Gibson
authors.forename: Simon M
authors.initials: SM
authors.lastname: Green
authors.forename: Peter J
authors.initials: PJ
authors.lastname: Maddox
authors.forename: Andrew J P
authors.initials: AJ
authors.lastname: White
authors.forename: David J
authors.initials: DJ
authors.lastname: Williams