Discovery and optimization of new chromium catalysts for ethylene oligomerization and polymerization aided by high-throughput screening

Article abstract of DOI:10.1021/ja0518171

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 orthotriptycenyl-substituted Schiff bases with pyridylmethyl or quinolyl substituents. Validation tests confirmed polymerization productivities of up to 3000 g·mmol^-1h^-1bar^-1 for the polymerization catalyst systems while the oligomerization catalysts gave productivities up to 10 000 g·mmol^-1h^-1bar ^-1. Key catalyst precursors have been characterized by X-ray crystallography.