Novel C1 symmetric zirconocenes containing substituted fluorenyl moieties for the polymerization of olefins
摘要:
The synthesis and polymerization behavior of four new asymmetric ansa-metallocenes containing a 2,7-disubstituted fluorenyl moiety and an indenyl moiety is reported. Three of the four catalysts, dichloro[eta(5)-1-indenyl(1-methylethylidene)-[2,7-bis-(2,4,6-trimethylphenyl)-eta(5)-9-fluorenyl]zirconium (11), dichloro[eta(5)-1-indenyl(I-methylethylidene)-[2,7-bis-(2,6-dimethylphenyl)-eta(5)-9-fluorenyl]zirconium (12), and dichloro[eta(5)-1-indenyl(l-methylethylidene)-[2,7-bis-(2-methylphenyl)-eta(5)-9-fluorenyl] zirconium (13) were highly active for the polymerization of both ethylene and propylene when activated with excess methylaluminoxane (MAO). Dichloro[eta(5)-1-indenyl(1-methylethylidene)-[2,7-dibenzyl-eta(5)-9-fluorenyl]zirconium (14) was poorly active for the polymerization of ethylene and was therefore not evaluated as a propylene catalyst. The activities for propylene polymerizations with catalysts 11 - 13 increased as the size of the substituents around the ligand framework increased, following the trend 11 > 12 > 13. Molecular weights of the polypropylenes decreased as the temperature was increased. The molecular weight data follows the same trend (11 > 12 > 13) as the activity data, wherein the largest substituents gave rise to the highest molecular weights. (C) 2003 Elsevier Science B.V. All rights reserved.
Novel C1 symmetric zirconocenes containing substituted fluorenyl moieties for the polymerization of olefins
摘要:
The synthesis and polymerization behavior of four new asymmetric ansa-metallocenes containing a 2,7-disubstituted fluorenyl moiety and an indenyl moiety is reported. Three of the four catalysts, dichloro[eta(5)-1-indenyl(1-methylethylidene)-[2,7-bis-(2,4,6-trimethylphenyl)-eta(5)-9-fluorenyl]zirconium (11), dichloro[eta(5)-1-indenyl(I-methylethylidene)-[2,7-bis-(2,6-dimethylphenyl)-eta(5)-9-fluorenyl]zirconium (12), and dichloro[eta(5)-1-indenyl(l-methylethylidene)-[2,7-bis-(2-methylphenyl)-eta(5)-9-fluorenyl] zirconium (13) were highly active for the polymerization of both ethylene and propylene when activated with excess methylaluminoxane (MAO). Dichloro[eta(5)-1-indenyl(1-methylethylidene)-[2,7-dibenzyl-eta(5)-9-fluorenyl]zirconium (14) was poorly active for the polymerization of ethylene and was therefore not evaluated as a propylene catalyst. The activities for propylene polymerizations with catalysts 11 - 13 increased as the size of the substituents around the ligand framework increased, following the trend 11 > 12 > 13. Molecular weights of the polypropylenes decreased as the temperature was increased. The molecular weight data follows the same trend (11 > 12 > 13) as the activity data, wherein the largest substituents gave rise to the highest molecular weights. (C) 2003 Elsevier Science B.V. All rights reserved.
Green, Efficient and Reusable Bis(imidazolium) Ionic Liquids Promoted Pd-Catalyzed Aqueous Suzuki Reaction for Organic Functional Materials
作者:Zhonggao Zhou、Yangyang Yuan、Yongrong Xie、Mei Li
DOI:10.1007/s10562-018-2452-y
日期:2018.9
bis(imidazolium) ionicliquids were used to promote environmentally friendly, efficient and reusable Pd-catalyzed Suzuki reaction between arylboronic acids and 2-bromofluorene, 2,7-dibromo-9,9′-dialkylfluorene. Over 30 carbazole-based fluorene core potential organic functional materials were synthesized. In addition, recyclability of catalyst system was inspected on the Suzuki reaction observing nearly
the imidazole heterocycle ring N through ethoxy bridged anomeric carbon. In addition, the catalytic activities revealed that Glu-NHCs-Pd(II)-PEPPSI complexes 2a-d are efficient catalysts for the aqueous Suzuki reaction. Under optimized conditions, a series of fluorene-cored functional materials with different aryl-substituents were synthesized through the Suzuki reaction with excellent yields. The
Poly(ethylene glycol)- and glucopyranoside-substituted N-heterocyclic carbene precursors for the synthesis of arylfluorene derivatives using efficient palladium-catalyzed aqueous Suzuki reaction
This paper reports an environmentally friendly and highly efficient synthesis of organic semiconductor materials via a Pd/N‐heterocyclic carbene (NHC)‐catalyzed Suzuki reaction in aqueous ethanol with high isolated yields (86–98%). Firstly, four glucopyranoside‐substituted NHC precursors with poly(ethylene glycol) (PEG) chains were synthesized and characterized. The NHC precursor with the longest PEG
Abstract Several novel benzimidazolium-based ionic liquids (BzIm ILs) with free and acetyl protected glucopyranoside unit were synthesized and used as ligand for Pd-catalyzed environment-friendly Suzuki reaction. The BzIm ILs with the acetyl protection shows the highest activity, probably because the sugar has a large steric hindrance and acetylgroups can coordinate with Pd. The nuclear magnetic resonance
Stericallyhindered 2,7-diaryl fluorenes have been efficiently synthesized via double Suzuki–Miyaura cross-coupling reactions of challenging 2,7-dichlorofluorene with a broad range of di-ortho-substituted arylboronic acids using the N-heterocyclic carbene Pd catalyst INPd. The efficiency of chloride-directed reactions is superior to that of bromide-directed reactions. Mechanistic studies revealed a