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Gas-phase structure, hydrogen bonding, and cation–anion interactions of a series of 1-(2-hydroxyethyl)-3- methylimidazolium ([HOEMIm]+)-based ionic liquids (hereafter called hydroxyl ILs) with different anions (X=[NTf2]–, [PF6]–, [ClO4]–, [BF4]–, [DCA]–, [NO3]–, [AC]– and [Cl]–), as well as 1-ethyl-3-methylimizolium ([EMIm]+)-based ionic liquids (hereafter called nonhydroxyl ILs), were investigated by density functional theory calculations and experiments. Electrostatic potential surfaces and optimized structures of isolated ions, and ion pairs of all ILs have been obtained through calculations at the Becke, three-parameter, Lee–Yang–Parr/6-31+G(d,p) level and their hydrogen bonding behavior was further studied by the polarity and Kamlet–Taft Parameters, and 1H-NMR analysis. In [EMIm]+-based nonhydroxyl ILs, hydrogen bonding preferred to be formed between anions and C2–H on the imidazolium ring, while in [HOEMIm]+-based hydroxyl ILs, it was replaced by a much stronger one that preferably formed between anions and OH. The O–H___X hydrogen bonding is much more anion-dependent than the C2–H___X, and it is weakened when the anion is changed from [AC]– to [NTf2]–. The different interaction between [HOEMIm]+ and variable anion involving O–H___X hydrogen bonding resulted in significant effect on their bulk phase properties such as 1H-NMR shift, polarity and hydrogen-bond donor ability (acidity, a).

Keywords: calculation; cation–anion interaction; hydrogen bonding; hydroxyl; ionic liquids; polarity

★★★☆☆  Zhang SG,Qi XJ,Ma XY,et al. Investigation Of Cation–anion Interaction In 1-(2-hydroxyethyl)-3-methylimidazolium-based Ion Pairs By Density Functional Theory Calculations And Experiments[J]. J. Phys. Org. Chem.,2011,25(3):248-257.

A new class of azobenzene-based photoresponsive ionic liquids was prepared and showed reversible modulation of ionic conductivity in specific solvents under alternative UV/visible light irradiation.

★★★★☆ Zhang SG,Liu SM,Zhang QH,et al. Solvent-dependent Photoresponsive Conductivity Of Azobenzene-appended Ionic Liquids[J]. Chem. Commun.,2011,47:6641-6643.

张庆华,张世国,邓友全
1.06 MB

Due to their unique properties, ionic liquids have offered great potential for developing clean catalytic technologies. After a short introduction of their advantages in green catalysis, recent advances in ionic liquid catalysis are reviewed with emphasis on four hot fields, viz. biomass conversion in ionic liquids, catalytic production of fine chemicals in ionic liquids, supported ionic liquid phase catalysis, as well as Friedel–Crafts reactions in ionic liquids. In particular, through selected samples, we show here the advantages and potential of ionic liquids in exploring cleaner catalytic technologies, as compared to traditional catalytic processes. Finally, further development of ILs in catalysis is briefly prospected.

★★★★☆ Green Chem., 2011, 13, 2619–2637

AC electrochemical windows (AC EWs) of ILs were first investigated on Pt, glass carbon (GC), and Au electrodes with frequency ranging from 20 to 100 Hz. The result showed that the AC EW of ILs was much wider than the DC EWs, and the AC EW increased markedly with frequency and with electrode in the order of GC > Pt > Au. Moreover, AC CVs of ILs provide not only different AC EWs but also different current density under identical voltage that are both structure-dependent.

★★★☆☆ Yang FL,Li ZP,Zhang SG,et al. Ac Electrochemical Stability Of Ionic Liquids[J]. Chem. Lett.,2011,40(12):Cl-110542(1-3).

The binary zinc–yttrium oxides were prepared by co-precipitation method, characterized and tested in the synthesis of DMC via transesterification of ethylene carbonate with methanol. The catalytic results showed that the catalyst with Zn/Y molar ratio of 3 and calcined at 400 °C exhibited superior catalytic activity, corresponding to TOF of 236 mmol/gcat h. Appropriate content of yttrium in the catalyst enhanced the catalytic activity remarkably. Moreover, the abundance of medium basic sites (7.2bH_b9.8, as determined by Hammett indicator method) was considered to be responsible for the superior catalytic activity.

Keywords: Dimethyl carbonate; Ethylene carbonate; Transesterification; Binary zinc–yttrium oxide

★★★☆☆ L. Wang et al. / Catalysis Communications 16 (2011) 45–49

Lanthanum oxide catalyst prepared by precipitation method and calcined at 600 °C exhibited better catalytic activity in the catalytic synthesis of glycerol carbonate from glycerol and urea with TOF up to 1506 mmol/g·h. It was proposed that the lanthanum oxide catalyst with more strong basic sites (TdN400 °C) exhibited higher catalytic activity. Accordingly, the catalyst containing appropriate amount of La2O2CO3 phase exhibited higher catalytic activity. Moreover, the recycling experiments demonstrated that the catalytic activity can be essentially preserved during the recycling tests investigated.

Keywords: Glycerol carbonate; Urea; Glycerol; Lanthanum oxide; Solid base

★★★☆☆ L. Wang et al. / Catalysis Communications 12 (2011) 1458–1462

Here, we show the one-step synthesis of N-alkylated anilines from nitrobenzenes and alcohols catalyzed by nano-gold catalyst. The yields to N-alkylated anilines were B90% under mild conditions. The mechanism of this reaction was explored. It shows promise for clean and simple synthesis of N-alkylated anilines.

★★★★☆ Peng QL,Zhang Y,Shi F,et al. Fe2o3-supported Nano-gold Catalyzed One-pot Synthesis Of N-alkylated Anilines From Nitroarenes And Alcohols[J]. Chem. Commun.,2011,47:6476-6478.

A new series of low-melting ammonium salts based on the [nido-7,8-C2B9H12]– anion have been synthesized and characterized, and their physicochemical properties including spectroscopic properties, thermal properties, surface properties, solubility, density, viscosity, electrochemical properties, and tribological properties have been studied in detail. In comparison with previously reported carborane-derivatized imidazolium or pyridinium salts, these diether-functionalized ammonium salts display lower phase transition temperatures (Tg = –76 to –57 °C), and four exist as liquids at room temperature due to their flexible alkoxy chains. TGA analysis revealed that the weight loss rates of these carborane-derivatized low-melting salts were ca. 30–80 wt.-% after thermal decomposition, which is different from the traditional RTILs. SEM images showed that the resulting residue had hollow reticular shell morphology, and XPS and XRD analyses indicate that the main components of the skeleton are B2O3 and amorphous carbon. This provides a new strategy for preparing new inorganic porous materials by thermal decomposition of these low-melting salts.

Keywords: Ionic liquids / Carboranes / Boron / Carbon / Raman spectroscopy / IR spectrocsopy

★★★☆☆ Liu SM,Chen ZJ,Zhang QH,et al. Carborane-derivatized Low-melting Salts With Ether-functionalized Cations—preparation And Properties[J]. Eur. J. Inorg. Chem.,2011:1910–1920.

The direct production of methyl, ethyl and n-butyl carbamates (MC, EC and BC) from NH3, CO2 and alcohols could efficiently be catalyzed by V2O5, and ca. 11–25% yields with 98% selectivity for alkyl carbamates could be obtained. The catalyst could be recycled six times without obvious decrease in catalytic activity. XRD and XPS analysis showed that in-situ produced (NH4)2V3O8 was the catalytically active species.

Keywords: Carbon dioxide; Vanadium(V)-oxide catalyst; Fixation; Alkyl carbamates

★★★☆☆ Catalysis Communications 12 (2011) 1224–1227

Electrowetting of ionic liquids (ILs) in different alkane ambient and at different temperatures were studied under different AC voltages. The performance of IL-based electrowetting at elevated temperatures and that at room temperature was compared. It turns out that the electrowetting of ILs at elevated temperatures resulted in faster response and lower operation voltage. Furthermore, the relationship between the structure of the ion and the contact angle change was specifically investigated and theoretically explained. Finally, the properties of IL-based electrowetting in different alkane ambient were studied. It was demonstrated that the long length of the alkyl chain guaranteed a smaller contact angle under the same applied voltage. All the experimental results showed attractive features involving wide operating temperatures and in particular high stability, fast response, and good reversibility at elevated temperatures. The performance of IL-based electrowetting could be further improved through an optimal choice of an ambient phase or a rational design and synthesis of ionic liquids.

Keywords: electrowetting; ionic liquids; temperature; alkanes ambient; AC voltage; response time

★★★☆☆ Hu XD,Zhang SG,Lu XJ,et al. On The Performance Of Thermostable Electrowetting Agents[J]. Surf. Interface Anal.,2011.

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