Selective synthesis of carbamates from amines and dimethyl carbonate were studied in the presence of various ionic liquids as catalysts. The –SO3H-functionalized ionic liquid was found to be the most active catalyst among the applied ionic liquids, and nearly 100% conversion and 95% selectivity were achieved when using 1,6-hexanediamine as reactant. The acid functional ionic liquid catalyst system is also readily separable and reusable after reaction.

Keywords: Green chemistry; Ionic liquid; Carbamates; Amine; Non-phosgene

★★★☆☆ Zhou HC,Shi F,Tian X,et al. Synthesis Of Carbamates From Aliphatic Amines And Dimethyl Carbonate Catalyzed By Acid Functional Ionic Liquids[J]. Journal Of Molecular Catalysis A: Chemical,2007,271:89-92.

The solubilities of C2H4 and CO2 and the interactions of polar and nonpolar solutes with the novel ionic liquids (ILs) 1-butyronitrile-3-methylimidazolium bis(trifluoromethylsulfonyl) imidate (CpMIm[NTf2]), 1-butyronitrile-2,3-dimethylimidazolium bis(trifluoromethylsulfonyl) imidate (CpMMIm[NTf2]), 1-butyronitrile-3-methylimidazolium dicyanamide (CpMIm[N(CN)2]), 1-butyronitrile-2,3-dimethylimidazolium dicyanamide (CpMMIm-[N(CN)2]), 1-butyl-3-methylimidazolium palmitate (BMIm[n-C16H33COO]), and 1-butyl-3-methylimidazolium stearate (BMIm[n-C18H35COO]) were studied by gas chromatography at infinite dilution at T ) (303.15, 313.15, 323.15, and 333.15) K. Henry’s law constant kH of C2H4 and CO2 gas, infinite dilution activity coefficient γ∞, molar enthalpies of solution ΔsolH∞, and partial molar excess enthalpies of solution ΔHE∞ and of Gibbs energies ΔGE∞ were determined for polar and nonpolar solutes in these novel ILs. Compared with the 1,3-dialkylimidazolium ILs, cyano functional group substitution on the alkyl chain results in a remarkable decrease of the interactions of hydrocarbons. BMIm[n-C16H31OO] and BMIm[n-C18H35OO] demonstrate strong solubilization for both polar and nonpolar solutes. Straight lines of ln Vg versus 1/T and ln γ∞ versus 1/T were obtained for the majority of solutes in the temperature range. BMIm[NTf2] and 1-octyl-3-methylimidazolium tetrafluoroborate (OMIm[BF4]) show much better solubility for thiophene and are better solvents for the separations of thiophene from hydrocarbons.

★★★☆☆ Zhang J,Zhang QH,Qiao BT,et al. Solubilities Of The Gaseous And Liquid Solutes And Their Thermodynamics Of Solubilization In The Novel Room-temperature Ionic Liquids At Infinite Dilution By Gas Chromatography[J]. J. Chem. Eng. Data,2007,52:2277-2283.

Based on the diversity of ionic liquids, i.e. tunable structure and physicochemical properties, a series of functional ionic liquids and palladium complexes were investigated, and a highly effective catalyst system, Pd(phen)Cl2-BAcImPF6 ionic liquid (phen = 1,10-phenanthroline; BAcIm = 1-butyl-3-acetic acid-imidazolium), was developed for the reductive carbonylation of nitrobenzene to give the corresponding carbamate with higher than 90% of conversion and selectivity at 150 ◦C and 6MPa carbon monoxide. The high catalytic performance is attributed to the acidic function of the BAcImPF6 ionic liquid and the interaction between Pd(phen)Cl2 and the ionic liquid to form the catalytically active palladium complex Pd(phen)2(PF6)2.

Keywords: Nitrobenzene; Carbon monoxide; Carbonylation; Ionic liquids; Palladium complex

★★★☆☆ Shi F,He YD,Li DM,et al. Developing Effective Catalyst System For Reductive Carbonylation Of Nitrobenzene Based On The Diversity Of Ionic Liquids[J]. Journal Of Molecular Catalysis A: Chemical,2006,244:64-67.

Esterification of tert-butanol by acetic anhydride, a typical acid–base catalytic reaction, was conducted with excellent selectivity and high yield in a neutral ionic liquid [BMIm]BF4 (1-butyl-3-methylimidazolium tetrafluoroborate). Many other tertiary alcohols could also be successfully converted to the corresponding esters in [BMIm]BF4. Separation of product and recovery and reuse of ionic liquid are all convenient in this system. Here, the need for catalysts is avoided through the use of catalytically active ionic liquids as solvents.

Keywords: [BMIm]BF4; Esterification; Tertiary alcohol; Acetic anhydride

★★★☆☆ Duan ZY,Gu YL,Deng YQ. Neutral Ionic Liquid [bmim]bf4 Promoted Highly Selective Esterification Of Tertiary Alcohols By Acetic Anhydride[J]. Journal Of Molecular Catalysis A: Chemical,2006,246:70-75.

The Beckmann rearrangement of cyclohexanone oxime to afford caprolactam in a novel caprolactam-based Brønsted acidic ionic liquid as catalyst and reaction medium proceeded with high conversion and selectivity at 100 ℃. The occurrence of the Beckmann rearrangement of cyclohexanone oxime in such a Brønsted acidic IL was also confirmed with in situ FT-Raman observation. The key point is that the caprolactam product was one component of the ionic liquid, and a dynamic exchange between the resulting caprolactam product and the caprolactam from the ionic liquid is expected. Therefore, the strong chemical combination between the caprolactam product and the acidic ionic liquid was greatly decreased and the desired product in the solid was recovered through extraction with organic solvent after the reaction.

★★★★☆Guo S,Du ZY,Zhang SG,et al. Clean Beckmann Rearrangement Of Cyclohexanone Oxime In Caprolactambased Brønsted Acidic Ionic Liquids[J]. Green Chemistry,2006,8:296-300.

Three new protic ionic liquids based on 2-methylpyridinium were prepared and characterized. Their catalytic activities for the tert-butylation of phenol and the esterification of cyclic olefins with acetic acid were examined and satisfactory results were obtained over 2-methylpyridinium trifluoromethanesulfonate ([2-MPyH]OTf). Hammett method was used to determine the acidity order of these ionic liquids and the results are consistent with the catalytic activities observed in the acid-catalyzed probe reactions.

Keywords: Protic ionic liquids; 2-Methylpyridinium; Hammett acidity; Brønsted acidity; Acid catalysis

★★★☆☆ Duan ZY,Gu YL,Zhang J,et al. Protic Pyridinium Ionic Liquids: Synthesis, Acidity Determination And Their Performances For Acid Catalysis[J]. Journal Of Molecular Catalysis A: Chemical,2006,250:163-168.

Supported Au catalysts Au-Au+-Clx/Fe(OH)y (x＜4, y≤3) and Au-Clx/Fe2O3 prepared with co-precipitation without any washing to remove Cl- and without calcining or calcined at 400 ℃ were studied. It was found that the presence of Cl had little impact on the activity over the unwashed and uncalcined catalysts; however, the activity for CO oxidation would be greatly reduced only after Au-Au+-Clx/Fe(OH)y was further calcined at elevated temperatures, such as 400 8C. XPS investigation showed that Au in catalyst without calcining was composed of Au and Au+, while after calcined at 400 8C it reduced to Au0 completely. It also showed that catalysts precipitated at 70 8C could form more Au+ species than that precipitated at room temperatures. Results of XRD and TEM characterizations indicated that without calcining not only the Au nano-particles but also the supports were highly dispersed, while calcined at 400 8C, the Au nano-particles aggregated and the supports changed to lump sinter. Results of UV–vis observation showed that the Fe(NO3)3 and HAuCl4 hydrolyzed partially to form Fe(OH)3 and [AuClx(OH)4 x] (x = 1–3), respectively, at 70 ℃, and such pre-partially hydrolyzed iron and gold species and the possible interaction between them during the hydrolysis may be favorable for the formation of more active precursor and to avoid the formation of Au–Cl bonds. Results of computer simulation showed that the reaction molecular of CO or O2 were more easily adsorbed on Au+ and Au0, but was very difficultly absorbed on Au . It also indicated that when Cl- was adsorbed on Au0, the Au atom would mostly take a negative electric charge, which would restrain the adsorption of the reaction molecular severely and restrain the subsequent reactions while when Cl was adsorbed on Au+ there only a little of the Au atom take negative electric charge, which resulting a little impact on the activity.

Keywords: Gold catalyst; CO oxidation; Green chemistry; Preparation; Uncalcined; Unwashed

★★★☆☆ Qiao BT,Deng YQ. Effective Au-au+-clx/fe(oh)y Catalysts Containing Cl- For Selective Co Oxidations At Lower Temperatures[J]. Applied Catalysis B: Environmental,2006,66:241-248.

Environmentally friendly and effective removal of Br and Cl impurities in hydrophilic dialkylimdazolium or butylpyridinium ionic liquids was investigated and developed at room temperature to 80 C and atomspheric pressure. Constant elelctrolysis was applied to oxidize Br and Cl to their corresponding Br2 and Cl2, then the BF 4 and NO 3 ions from HBF4 and HNO3 solution in the cathode zone move to anode zone through an anion exchange membrane and combine with dialkylimdazolium or butylpyridinium cation to form ionic liquids. The Br2 and Cl2 in electrolyzed ionic liquids are treated with ethylene to afford the corresponding 1,2-dibromo (or dichloro) ethane which could easily be removed by volatilisation under vacuum (ca. 10 mm Hg). Removal of Br and Cl impurities (0.94–4.47 wt%) from hydrophilic dialkyl imdazolium or butylpyridinium ionic liquids through electrolysis and ethylene treatment could be achieved at 0.06%–0.29% without any additional solvents and ionic liquid loss.

Keywords: Electrolysis; Ionic liquid; Bromide; Chloride; Removal

★★★★☆ Li ZP,Du ZY,Gu YL,et al. Environmentally Friendly And Effective Removal Of Br And Cl- Impurities In Hydrophilic Ionic Liquids By Electrolysis And Reaction[J]. Electrochemistry Communications,2006,8:1270-1274.

Choline chloride·xZnCl2 (x = 1–3) or benzyltrimethylammonium chloride·xZnCl2 have been used as efficient and recyclable catalysts for protection of carbonyls to 1,3-dioxolanes and 1,3-dioxanes at room temperature under solvent-free conditions. FT-IR investigation demonstrates the four ionic liquids have similar Lewis acid strength, which is in agreement with the activities observed in the acetalization reaction. The catalytic system choline chloride·xZnCl2 can be reused up to five times without appreciable loss of activity. The simple procedures as well as easy recovery and reuse of this novel catalytic system are expected to contribute to the development of more benign acetalization procedure of carbonyl compounds.

关键词: Choline chloride·xZnCl2;  Acetalization;  Solvent-free;  Reusability;  Lewis acidity;  Green chemistry

★★★☆☆ Duan ZY,Gu YL,Deng YQ. Green And Moisture-stable Lewis Acidic Ionic Liquids (choline Chloride  xZnCl2) Catalyzed Protection Of Carbonyls At Room Temperature Under Solvent-free Conditions[J]. Catalysis Communications,2006,7:651-656.

The cucumber cotyledon greening bioassay for cytokinins was modified by using 95 % acetone-ethanol instead of 80 % acetone as extraction solvent. The cotyledons were extracted directly with a 2:1 (v/v) acetone-ethanol solution in dark for 24 hours, omit ting the homogenization and centrifugation operations of the previous bioassay. The modified bioassay is more convenient and especially useful in screening cytokinin-active substance from a large number of samples.

Key words: cytokinins, cu cum ber cot y le don greening bioassay, chlorophyll ex trac tion, 6-benzyl-adenine, N,N’-diphenylurea

★★★☆☆ Yu XJ, Li GX, Xu D,et al. An Im Provement Of Cucumber Cotyledon Greening Bioassay For Cytokinins[J]. Acta Physiologiae Plantarum,2006,28(1):9-11.