- Syntheses of very dense halogenated liquids
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A family of halogenated liquids with densities ranging from 1.95 to 2.80 g cm-3 was readily synthesized by a one-pot procedure. These liquids exhibit characteristics of ionic liquids with melting/transition points lower than room temperature, long liquid ranges, and marked hydrolytic and thermal stabilities.
- Ye, Chengfeng,Shreeve, Jean'ne M.
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- Low viscosity azide-containing mono and dicationic ionic liquids with unsaturated side chain
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A new class of azide-functionalized monocationic and unsymmetrical dicationic ionic liquids (ILs) with low viscosity and high liquid range was synthesized. All of the synthesized ILs, were characterized by FT-IR, 1HNMR, 13CNMR spectroscopies and elemental analysis. Some thermophysical properties including melting point, density, shear viscosity, decomposition temperature and heat capacity of the unsymmetrical dicationic azide functionalized IL with dicyanamide (DCA) were measured. To find the unique and general features of this dicationic IL, its properties were compared with the ones of the similar monocationic ILs. The results showed that the shear viscosity, density, thermal stability and heat capacity of the unsymmetrical dicationic IL are higher than monocationic analogues. In addition we found that the shear viscosity for the synthesized unsymmetrical dicationic IL containing azide group and DCA anion is 83.9?cP whereas the shear viscosities for other dicationic ILs reported in the literature are higher than 240?cP.
- Fareghi-Alamdari, Reza,Hatefipour, Razieh
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- Trapping of Polysulfides with Sulfur-Rich Poly Ionic Liquid Cathode Materials for Ultralong-Life Lithium–Sulfur Batteries
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Sulfur-rich polymers synthesized by inverse vulcanization are promising cathodes for Li–S batteries and can suppress the shuttle effect to improve the cycling properties of Li–S batteries. However, developing a sulfur-rich copolymer with new chemical functionality to enhance performance of Li–S batteries remains a huge challenge. In this report, a sulfur-rich polymer cathode containing ionic liquid segments named poly(sulfur-co-1-vinyl-3-allylimidazolium bromide) [poly(S-co-DVIMBr)] was obtained by the inverse vulcanization of S8 with DVIMBr and used as cathode for the first time. This sulfur-rich poly ionic liquid cathode showed effective suppression of the shuttle effect through joint effects of the stable chemical bonding of C?S and strong cation absorption for lithium polysulfides, which was confirmed by DFT calculations. In particular, the Li–S cell with poly(S-co-DVIMBr) cathode delivered high capacity retention of 90.22 % even over 900 cycles. Developing sulfur-rich poly ionic liquids may provide a new strategy of introducing the functional groups with cations into the cathode materials for suppressing the shuttle effect and improving the performance of Li–S batteries.
- Liu, Xu,Lu, Yu,Zeng, Qinghui,Chen, Pingping,Li, Zhenfeng,Wen, Xin,Wen, Wen,Li, Zengxi,Zhang, Liaoyun
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- Azolium salts functionalized with cyanomethyl, vinyl, or propargyl substituents and dicyanamide, dinitramide, perchlorate and nitrate anions
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A series of functionalized imidazolium and 1,2,4-triazolium salts with cyanomethyl, vinyl and propargyl substituents coupled with energetic anions, viz., perchlorate, nitrate, dicyanamide and dinitramide were prepared and characterized by NMR and IR spectroscopy, and elemental analyses. Since some melt -3. The standard enthalpies of formation of the salts were calculated by using the computationally feasible DFT(B3LYP) and MP2 methods in conjunction with an empirical approach based on calculated densities of the salts. These values range from ΔH°f = -56 (12a) to 851 (21c) kJ mol-1. Of the salts synthesized, the dicyanamides exhibit the highest positive heats of formation, but also the lowest densities. Wiley-VCH Verlag GmbH & Co. KGaA, 2007.
- Gao, Ye,Gao, Haixiang,Piekarski, Crystal,Shreeve, Jean'ne M.
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- Asymmetric rhodium-directed anti-markovnikov regioselective boracyclopentannulation
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A Shimoi-type activation of B-H bond of NHC-boranes by a diphosphane-ligated cationic Rh complex was applied in an unprecedented intramolecular hydroboration reaction of simple olefins. The use of NHC-boranes as hydroborating reagents is still undisclosed due to their nonreactivity toward alkenes which could be explained by the high stability of this complex rendering it unable to provide a "free" borane hydroborating reagent. B-H bond Rh activation of NHC-borane circumvents this limitation, and asymmetric Rh-directed anti-Markovnikov boracyclopentannulation reaction led to a library of enantioenriched cyclic boranes in high yield (up to 94%) with high regio- (up to 100%) and enantioselectivity (er up to 99.2:0.8). This new activation mode of NHC-boranes highlights their use in organometallic chemistry and offers a very good approach to access chiral cyclic NHC-boranes.
- Toure, Momar,Chuzel, Olivier,Parrain, Jean-Luc
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supporting information
p. 17892 - 17895
(2013/01/15)
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