677007-45-3Relevant academic research and scientific papers
Designing ionic liquids: 1-Butyl-3-methylimidazolium cations with substituted tetraphenylborate counterions
Van den Broeke, Joep,Stam, Marjolijn,Lutz, Martin,Kooijman, Huub,Spek, Anthony L.,Deelman, Berth-Jan,Van Koten, Gerard
, p. 2798 - 2811 (2003)
The hydrophobic, low melting, 1-butyl-3-methylimidazolium (BMIm) salts [BMIm][BPh4] (1), [BMIm][B(C6H4Me-4) 4] (2), [BMIm][B{C6H4(CF3)-4} 4] (3), [BMIm][B{C6H3(CF3) 2-3,5}4] (4), [BMIm][B{C6H4(C 6F13)-4}4] (5), [BMIm][B{C6H 4(SiMe3)-4}4] (6), [BMIm][B(C6H 4{SiMe2(CH2CH2CF 3)}-4)4] (7), [BMIm][B{C6H 4(SiMe2C8H17}-4}4] (8) and [BMIm][B(C6H4{SiMe2(CH2CH 2C6F13)}-4)4] (9) have been prepared. Systematic variation of the substituents on the tetraphenylborate anion allowed an assessment of their influence on the physical properties of the imidazolium salts. Structural investigations using NMR and IR spectroscopy, combined with single crystal X-ray structure determinations for 2, 3, 5 and 6, revealed hydrogen-bonding interactions between the imidazolium ring protons and the borate anion, both in the solid state and in solution. These interactions are weakened upon the introduction of electron-withdrawing substituents in the anion and follow the order 3,5-(CF3)2 6F13 3 2CH 2CH2C6F13 2CH2CH2CF3 3. The melting points of the salts depend primarily on the bulk of the lipophilic substituents, and decrease with increasing size. Bulky lipophilic substituents dramatically enhance the solubility of the imidazolium borates 8 and 9 in hexane and reduce their relative polarity. These unique properties make imidazolium borates 8 and 9 interesting as amphiphilic ionic liquids with low polarity. Attempts to crystallise 7 resulted in decomposition. A single-crystal X-ray structure determination of the product, isolated in 6% yield, showed that a carbene-tris[4-{dimethyl(3,3,3-trifluoropropyl)silyl}phenyl]borane adduct was formed. Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2003.
Extremely Active Ethylene Tetramerization Catalyst Avoiding the Use of Methylaluminoxane: [iPrN{P(C6H4-p-SiR3)2}2CrCl2]+[B(C6F5)4]?
Park, Hee Soo,Kim, Tae Hee,Baek, Jun Won,Lee, Hyun Ju,Kim, Tae Jin,Ryu, Ji Yeon,Lee, Junseong,Lee, Bun Yeoul
, p. 4351 - 4359 (2019/08/01)
Sasol's original ethylene tetramerization catalyst requires the use of expensive MMAO, a low working temperature (～60 °C), and generates polyethylene (PE) as a side product. In this study, we developed an upgraded catalytic system that successfully avoids the need for MMAO. [(PNP)CrCl2]+[B(C6F5)4]?-type species was obtained from the reaction of CrCl3(THF)3, [PhN(H)Me2]+[B(C6F5)4]?, and iPrN[P(C6H4-p-Si(nBu)3)2]2 (2) as well as from simply reacting 2 with [CrCl2(NCCH3)4]+[B(C6F5)4]?. The bulky (nBu)3Si-substituents play the crucial role of preventing the formation of the inactive [(PNP)2CrCl2]+[B(C6F5)4]?. The prepared [2-CrCl2]+[B(C6F5)4]? combined with iBu3Al was extremely active ('4000 kg/g-Cr/h), performed well at a high temperature of up to 90 °C, and generated a negligible amount of PE (0.03 wt%). Screening the performance with a series of iPrN[P(C6H4-p-SiR3)2]2 further supported that bulky R3Si-substituents are crucial not only to achieve extremely high activities but also to minimize the generation of PE. Structure of a [(PNP)CrCl2]+[B(C6F5)4]? species was elucidated by X-ray crystallography.
