title: A chromium precursor for the Phillips ethylene trimerization catalyst: (2-ethylhexanoate)2CrOH.
abstract: The conventional Phillips ethylene trimerization catalyst prepared by reacting Cr(EH)3 (EH = 2-ethylhexanoate), 2,5-dimethylpyrrole (Me2C4H2NH), Et3Al, and Et2AlCl in an aromatic hydrocarbon solvent was improved to obtain a congener composed of a new chromium precursor (EH)2CrOH, (Me2C4H2N)AlEt2, and Et3Al·ClAlEt2. Reaction of CrCl3 with 3 equiv. Na(EH) in water did not generate Cr(EH)3, but unexpectedly produced (EH)2CrOH. In comparison with the erratic catalytic performance of the original Phillips system, due to the ill-defined nature of the Cr(EH)3 source (16 or 6.8 × 10(6) g per mol-Cr h depending on the source), the improved system exhibited consistently high activity (54 × 10(6) g per mol-Cr h). Reaction of (EH)2CrOH with (Me2C4H2N)AlMe2·OEt2 afforded the dimeric Cr(II)-complex (6) coordinated by (η(5)-Me2C4H2N)AlMe2(NC4H2Me2) and μ2-κ(1):η(2)-Me2C4H2N ligands. 6 provided highly active species when activated with Et3Al·ClAlEt2.
authors.affiliation: Department of Molecular Science and Technology, Ajou University, Suwon 443-749, South Korea.
authors.forename: Jong Yeob
authors.initials: JY
authors.lastname: Jeon
authors.forename: Dong Sik
authors.initials: DS
authors.lastname: Park
authors.forename: Dong Hwan
authors.initials: DH
authors.lastname: Lee
authors.forename: Seong Chan
authors.initials: SC
authors.lastname: Eo
authors.forename: Seong Yeon
authors.initials: SY
authors.lastname: Park
authors.forename: Myoung Sun
authors.initials: MS
authors.lastname: Jeong
authors.forename: Yi Young
authors.initials: YY
authors.lastname: Kang
authors.forename: Junseong
authors.initials: J
authors.lastname: Lee
authors.forename: Bun Yeoul
authors.initials: BY
authors.lastname: Lee