TY - JOUR
T1 - Phenoxysalicylaldimine-Bearing Chromium(III) Precatalysts for Ethylene Polymerization
AU - Yankey, Margaret
AU - Obuah, Collins
AU - Darkwa, James
N1 - Publisher Copyright:
© 2014 Wiley-VCH Verlag GmbH & Co. KGaA.
PY - 2014/9/1
Y1 - 2014/9/1
N2 - A series of discrete chromium(III) precatalysts, {[Cr(κ3-L1)] (1a.7H2O), {[Cr(κ3-L2)] (2a.5H2O), {[Cr(κ3-L3)] (3a.6H2O), {[Cr(κ3-L4)] (4a.10H2O), {[Cr(κ3-L5)] (5a.4H2O) and in-situ-generated chromium(III) precatalysts {[Cr(κ3-L1)] (1b), {[Cr(κ3-L2)] (2b), {[Cr(κ3-L3)] (3b), {[Cr(κ3-L4)] (4b), {[Cr(κ3-L5)] (5b) bearing 2,4-di-tert-butyl-6-{[2-(1H-imidazol-4-yl)-ethylimino]-methyl}-phenol (L1), 2,4-di-tert-butyl-6-{[2-RR-pyrazol-1-yl-ethylimino]-methyl}-phenol, R = H (L2), Me (L3), Ph (L4), and 2,4-di-tert-butyl-6-{[2-pyrid-2-yl-ethylimino]-methyl}-phenol (L5) are developed. The discrete precatalysts are characterized by IR spectroscopy, elemental analysis, and mass spectrometry. The in-situ-generated precatalysts afford a one-step process for screening chromium(III) complexes as ethylene polymerization catalysts. Upon activation with EtAlCl2, both types of precatalysts exhibit high catalytic activities up to 1.71 × 105 g mol(Cr)-1 h-1 for the formation of high-density polyethylene with molecular weights as high as 3.48 × 103 g mol-1. While the discrete precatalysts produce monomodal active catalysts at all conditions, the in-situ-generated precatalysts produce either monomodal or bimodal active catalysts, suggesting that, at certain conditions, two active catalysts are produced in the in situ reactions. (Chemical Equation Presented).
AB - A series of discrete chromium(III) precatalysts, {[Cr(κ3-L1)] (1a.7H2O), {[Cr(κ3-L2)] (2a.5H2O), {[Cr(κ3-L3)] (3a.6H2O), {[Cr(κ3-L4)] (4a.10H2O), {[Cr(κ3-L5)] (5a.4H2O) and in-situ-generated chromium(III) precatalysts {[Cr(κ3-L1)] (1b), {[Cr(κ3-L2)] (2b), {[Cr(κ3-L3)] (3b), {[Cr(κ3-L4)] (4b), {[Cr(κ3-L5)] (5b) bearing 2,4-di-tert-butyl-6-{[2-(1H-imidazol-4-yl)-ethylimino]-methyl}-phenol (L1), 2,4-di-tert-butyl-6-{[2-RR-pyrazol-1-yl-ethylimino]-methyl}-phenol, R = H (L2), Me (L3), Ph (L4), and 2,4-di-tert-butyl-6-{[2-pyrid-2-yl-ethylimino]-methyl}-phenol (L5) are developed. The discrete precatalysts are characterized by IR spectroscopy, elemental analysis, and mass spectrometry. The in-situ-generated precatalysts afford a one-step process for screening chromium(III) complexes as ethylene polymerization catalysts. Upon activation with EtAlCl2, both types of precatalysts exhibit high catalytic activities up to 1.71 × 105 g mol(Cr)-1 h-1 for the formation of high-density polyethylene with molecular weights as high as 3.48 × 103 g mol-1. While the discrete precatalysts produce monomodal active catalysts at all conditions, the in-situ-generated precatalysts produce either monomodal or bimodal active catalysts, suggesting that, at certain conditions, two active catalysts are produced in the in situ reactions. (Chemical Equation Presented).
KW - chromium
KW - ethylene
KW - polymerization
KW - salicylaldimine
UR - http://www.scopus.com/inward/record.url?scp=84925650483&partnerID=8YFLogxK
U2 - 10.1002/macp.201400223
DO - 10.1002/macp.201400223
M3 - Article
AN - SCOPUS:84925650483
SN - 1022-1352
VL - 215
SP - 1767
EP - 1775
JO - Macromolecular Chemistry and Physics
JF - Macromolecular Chemistry and Physics
IS - 18
ER -