The N-alkylation of amines or ammonia with alcohols is a valuable route for the synthesis of N-alkyl amines. However, as a potentially clean and economic choice for N-alkyl amine synthesis, non-noble metal catalysts with high activity and good selectivity are rarely reported. Normally, they are severely limited due to low activity and poor generality. Herein, a simple NiCu-FeO_x catalyst was designed and prepared for the N-alkylation of ammonia or amines with alcohol or primary amines. N-alkyl amines with various structures were successfully synthesized in moderate to excellent yields in the absence of organic ligands and bases. Typically, primary amines could be efficiently transformed into secondary amines and N-heterocyclic compounds, and secondary amines could be N-alkylated to synthesize tertiary amines. Note that primary and secondary amines could be produced through a one-pot reaction of ammonia and alcohols. In addition to excellent catalytic performance, the catalyst itself possesses outstanding superiority, that is, it is air and moisture stable. Moreover, the magnetic property of this catalyst makes it easily separable from the reaction mixture and it could be recovered and reused for several runs without obvious deactivation.

Keywords: alcohols · amination ·ammonia · heterogeneous catalysis ·non-noble metals

★★★☆☆ Cui XJ,Dai XC,Deng YQ,et al. Development Of A General Non-noble Metal Catalyst For The Benign Amination Of Alcohols With Amines And Ammonia[J]. Chemistry A-europeann Journal,2013,19(11):3665-3675.

★★★☆☆ Yang HM,Cui XJ,Deng YQ,et al. Selective Hydrogenation Of Nitroaromatic Compounds With A Nickel-oxide-supported Nano-palladium Catalyst Under Ambient Reaction Conditions[J]. Chemcatchem,2013,5:1739-1743.

The controllable preparation of nano-gold catalyst maintains a challenge. Except the parameters have been revealed before, here we’d like to show that controllable preparation of active nano-gold catalyst can be achieved using chlorine as an indicator. By tracing the chlorine concentration in the washing step, a series of Au/Fe₂O₃ catalysts were prepared with co-precipitation method. The applying of these catalysts in CO oxidation and reductive nitrobenzene N-alkylation suggested the active catalysts were prepared from solutions containing ～2 ppm chlorine. The catalytic activity dropped dramatically if the chlorine concentration is >4–6 or <<1 ppm. Extensive characterizations revealed that the active catalyst was composed by nano-gold on the edge of Fe₂O₃ particle with 8.92 Au-Au coordination numbers. Although the real role of chlorine in the variation of catalyst structure and activity was still ambiguous, the current results should promote the controllable preparation of active nano-Au catalyst.

★★☆☆☆ Zhang CM,Liu LQ,Cui XJ,et al. Chlorine As An Indicator In The Controllable Preparation Of Active Nano-gold Catalyst[J]. Scientific Reports,2013,3:1503(1-7).

A series of carbon aerogels were prepared with or without using ionic liquids as templates. By varying the structures and contents of ionic liquids, carbon aerogels with different pore size distributions could be obtained. The effect of the ionic liquids on the properties of the final carbon aerogels was explored and the catalytic performance of the carbon aerogels in the selective oxidation of tetralin was studied.

★★★☆☆ Yang HM,Cui XJ,Deng YQ,et al. Ionic Liquid Templated Preparation Of Carbon Aerogels Based On Resorcinol–formaldehyde: Properties And Catalytic Performance[J]. J. Mater. Chem.,2012,22:21852-21856.

★★★★☆ Zhang SG,Shi R,Ma XY,et al. Intrinsic Electric Fields In Ionic Liquids Determined By Vibrational Stark Effect Spectroscopy And Molecular Dynamics Simulation[J]. Chem. Eur. J.,2012,18:11904-11908.

Ionic liquids (ILs)-stabilized iron oxide (Fe2O3) nanoparticles were synthesized by the ultrasonic decomposition of iron carbonyl precursors in [EMIm][BF4] without any stabilizing or capping agents. The Fe2O3 nanoparticles were isolated and characterized by X-ray powder diffraction, transmission electron microscopy and susceptibility measurements. The physicochemical properties of ILs containing magnetic Fe2O3 nanoparticles (denoted as Fe2O3@[EMIm][BF4]), including surface properties, density, viscosity and stability, were investigated in detail and compared with that of [EMIm][BF4]. The Fe2O3@[EMIm][BF4] can be directly used as magnetic ionic liquid marble by coating with hydrophobic and unreactive polytetrafluoroethylene (PTFE), for which the effective surface tension was determined by the puddle height method. The resulting magnetic ionic liquid marble can be transported under external magnetic actuation, without detachment of magnetic particles from the marble surface that is usually observed in water marble.

★★★☆☆ Zhang SG,Zhang Y,Wang Y,et al. Sonochemical Formation Of Iron Oxide Nanoparticles In Ionic Liquids For Magnetic Liquid Marble[J]. Phys. Chem. Chem. Phys.,2012,14:5132-5138.

The polarity of ionic liquids (ILs), usually denoted as ET(30) by the solvatochromic probe Reichardt’s dye, is one of the most fundamental properties that remarkably affect the solvation and chemical reaction in ILs. It was generally accepted that the ET(30) of ILs was dominated by the nature of the cation. However, in this work, it was found that the common ammonium-based ILs showed strongly anion-dependent ET(30). For example, the ET(30) value for [N1124][DCA] and [N1124][NTf2] is 49.0 and 59.0 kcal mol 1, respectively, while the corresponding imidazolium ILs bearing the same anions possess nearly identical ET(30), the ET(30) value for [BMIm][DCA] and [BMIm][NTf2] is 51.4 and 51.6 kcal mol 1, respectively. Moreover, introduction of an ether group was found to increase the ET(30) of imidazolium ILs while having no obvious effect on that of ammonium-based ILs. The Kamlet–Taft parameters and density functional theory (DFT) calculations indicated that the distinct result is related to different stabilization of the ground state of Reichardt’s dye 30. In imidazolium ILs, the main interactions between ILs and zwitterionic dye involve both coulombic interaction (between the cation and the phenolate oxygen atom) and H-bonding interaction (between the acidic hydrogen on imidazolium ring and the phenolate oxygen atom). However, with the ammonium ILs lack of active hydrogen, the dye is only stabilized by the coulombic interaction between the cation and the phenolate oxygen atom. Interestingly, in both imidazolium and ammonium-based ILs, the spiropyran–merocyanine equilibrium exhibit obvious anion-dependent photochromism, solvatochromism, and thermal relaxation.

★★★☆☆ Zhang SG,Chen ZJ,Qi XJ,et al. Distinct Influence Of The Anion And Ether Group On The Polarity Of Ammonium And Imidazolium Ionic Liquids[J]. New J. Chem.,2012,36:1043-1050.

A series of silica, glass and molecular sieves supported chloroaluminate ionic liquids (ILs) were prepared and their catalytic performance on the trimerization of isobutene based on C4 mixture was investigated. Interestingly, it was found that the carrier played a key role in the reaction route. Among these supported catalysts, silica supported chloroaluminate ionic liquid was highly efficient for the trimerization of isobutene. X-ray photoelectron spectroscopy (XPS) and differential scanning calorimetry (DSC) characterizations suggested that the synergy between Al2Cl7− anion and silica induced the catalytic activity for isobutene oligomerization due to the strong interaction between ILs and silanol group. The reaction conditions including loading amount, temperature, reactant concentration, and space velocity for the isobutene oligomerization were optimized. Ultimately, complete conversion of isobutene and 91.4% selectivity of trimers were obtained over the IL/silica (30 wt.%) catalyst at mild conditions. Moreover, catalyst stability and deactivation were preliminarily studied.

Keywords: Ionic liquid; Silica supported; Isobutene; Trimerization; C4 feed

★★★☆☆ Liu SM,Shang JP,Zhang SG,et al. Highly Efficient Trimerization Of Isobutene Over Silica Supported Chloroaluminate Ionic Liquid Using C4 Feed[J]. Catalysis Today,2012,200:41-48.

Catalytic syntheses of cyclohexyl carbamates via alcoholysis of dicyclohexyl urea (DCU), which can be synthesized from CO2 and amines, were first investigated with low-molecular-weight alcohols, i.e., methanol, ethanol, butan-1-ol. TiO2/SiO2 catalyst was prepared by wet impregnation method using tetrabutyl titanate as titanium source. The catalyst was characterized by inductively coupled plasma/atomic emission spectroscopy (ICP/AES), N-2 adsorption, X-ray diffraction (XRD), field emission/scanning electron microscopy (FE/SEM), transmission electron microscopy TEM), and NH3/temperature-programmed desorption (TPD) in detail. TiO2/SiO2 with 5 wt % loadings and calcination at 600 degrees C exhibited better catalytic activity, and excellent yields of > 95 % with 98 % selectivities for desired carbamates were achieved. Accordingly, the strong acidity was considered to be responsible for its superior activity. Moreover, the catalytic activity can essentially be preserved during the recycling tests. The scope was also expanded to synthesize other alkyl or aryl carbamates via alcoholysis of the corresponding disubstituted ureas, and 94 % yields with 96 % selectivities can be achieved. It provided a good candidate for the organic carbamates syntheses via a phosgene/halogen-free and effective route.

Keywords: alcoholysis;  disubstituted ureas;  N-substituted carbamates;  TiO2/SiO2;  phosgenefree

★★★☆☆ Wang LG,Shang JP,Liu SM,et al. Environmentally Benign And Effective Syntheses Of N-substituted Carbamates Via Alcoholysis Of Disubstituted Ureas Over Tio2/sio2 Catalyst[J]. Pure And Applied Chemistry,2012,84:461-471.

★★★☆☆ Zhang SG,Liu SM,Zhang Y,et al. Photoinduced Isothermal Phase Transition Of Ionic Liquid Crystals[J]. Chemistry – An Asian Journal,2012,7(9):2004-2007.