Isobutylaluminum aryloxides as metallocene activators in Homo‐ and copolymerization of olefins

Abstract

The article describes that sterically hindered isobutylaluminum aryloxides with bulky t Bu substituents at 2,6-positions of aryl fragment, i.e. (2,6-di-Bu (1-TTBP)) and (2,6-di-Me(2-BHT)) can serve as cocatalysts for metallocene complexes. Isobutylaluminum aryloxides have been applied for activation of rac-Et(2-MeInd) 2 ZrMe 2 in homopolymerization of ethylene, propylene, copolymerization of ethylene and propylene, and terpolymerization of ethylene, propylene, and 5-ethylidene-2-norbornene at Al/Zr 5 300 mol/mol. The type of R substituent at 4-position has a significant effect on catalyst activity. The catalytic system with 1-TTBP showed the highest activity in all homo-and copolymerization processes. Diisobutylaluminum aryloxides provide much higher activity to the systems in all polymerization processes and stronger ability for propylene incorporation in copolymer than diaryloxides. The activities of the systems with isobutylaluminum aryloxides are similar or exceed that of the system with MAO as activator as have shown for propylene polymerization.

Synthesis and Properties of Ethylene/propylene and Ethylene/propylene/5-ethylidene-2-norbornene Copolymers Obtained on Rac-Et(2-MeInd)2ZrMe2/Isobutylaluminium Aryloxide Catalytic Systems

“…Sterically hindered isobuthylaluminum aryloxides with ortho- t Bu substituted aryloxy ligands efficiently activate the dimethylated bis-indenyl catalysts in the homo- and co-polymerization of olefins and the terpolymerization with 5-ethylidene-2-norbornene [ 17 , 18 , 19 , 20 ]. The structure of the organoaluminum species as the cocatalyst can significantly influence the catalytic properties due to steric reasons at the least.…”

“…Isobutylaluminum aryloxides (2,6- t Bu 2 PhO-)Al i Bu 2 (1-DTBP) (2,6- t Bu 2 ,4-Me-PhO-)Al i Bu 2 (1-BHT), (2,4,6- t Bu 2 PhO-)Al i Bu 2 (1-TTBP), (2,6- t Bu 2 ,4-Me-PhO-) 2 Al i Bu (2-BHT), (2,6- t Bu 2 PhO-) 2 Al i Bu (2-DTBP), [(2-Me,6- t Bu-C 6 H 3 O)Al i Bu 2 ] 2 (1-MTBP), [(2,6-Ph 2 -PhO)Al i Bu 2 ] 2 (1-DPP) were obtained by reaction of Al i Bu 3 (Aldrich Chem. Co., Milwaukee, MI, USA) with the corresponding phenol according to the procedures described in our works [ 19 , 20 , 21 ]. All manipulations with rac -Et(2-MeInd) 2 ZrMe 2 and isobutylaluminum aryloxides were performed in an argon atmosphere.…”

“… Copolymerization conditions: [Zr] ≈ 9 × 10 −5 mol/l, Al/M = 300 mol/mol, monomer pressure—10.6 atm, toluene—60mL., 30 °C; a) Monomers: E—ethylene, P—propylene, ENB—5-ethylidene-2-norbornene;E/P = 0.7/1, E/P/ENB = 4.7/4.3/1; b ) Specific activity of the system determined by consumption of gaseous monomer in 3 min. of reaction time and related to the amount of catalyst and atmosphere in ton copolymer/(mol M × 3 min × atm); c ) Melting point of the copolymers determined by the maximum of DSC curve; d ) Heat of fusion; e ) Crystallinity determined from X-ray powder diffraction analysis; f ) Tensile strength; g ) Elongation at break; h ) Engineering strain; i ) Copolymer is not soluble in 1,2,4-trichlorobenzene at 135 C; j) Mechanical tests are performed on four blades; k ) M w , M w /M n , copolymer composition and T m are from reference [ 19 ]; l ) M w , M w /M n , copolymer composition and T m are from reference [ 20 ]. …”

“…Our previous work shows that isobutylaluminum aryloxides work well as activators of dimethyl bis-indenyl metallocene complexes in olefin (co)polymerization [ 18 , 19 , 20 , 21 ]. New catalytic systems have been found to be effective for producing ethylene/propylene copolymers and ethylene/propylene/5-ethylidene-2-norbornene terpolymers.…”

Homogeneous Group IVB Catalysts of New Generations for Synthesis of Ethylene-Propylene-Diene Rubbers: A Mini-Review

“…Thus, researchers from the Uniroyal Chemical Comp successfully employ a mixture of boraryl compounds LiB(C 6 F 5 ) 4 and B(C 6 F 5 ) 3 , which provide higher process stability even at elevated temperatures [15]. Other new effective activators for the synthesis of EPDM based on isobutylaluminumoxanes (-O-Al(Bu i )-) n and isobutylaluminum aryl oxides (Al(Bu i ) 3−k Oar k ) have been proposed [27][28][29][30][31][32]. These compounds effectively activate MC precatalysts at low molar excess (200-300 molar equiv.)…”