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In this work, densities and viscosities for the binary mixtures of 1-octyl-3-methylimidazolium tetrafluoroborate, [Cmim][BF], with butanone, methyl acetate, ethyl acetate, propyl acetate and butyl acetate have been determined at 298.15 K. These data were used to calculate the excess molar volumes $$ V_{m}^{\text{E}} $$ and the viscosity deviations (ln η) for the mixtures. It is shown that values of $$ V_{m}^{\text{E}} $$ are negative, while those of (ln η) are positive in the whole concentration range. The $$ V_{m}^{\text{E}} $$ values show their minimum at the composition of x ≈ 0.3, and the (ln η) values exhibit a maximum at the same mole fraction. For the binary systems, the absolute values of $$ V_{m}^{\text{E}} $$ decrease in the order: butanone > methyl acetate > ethyl acetate > propyl acetate > butyl acetate, whereas those of (ln η) decrease in the order: methyl acetate > ethyl acetate > propyl acetate > butyl acetate > butanone. The results are discussed in terms of the ion-dipole interactions between cations of the ionic liquid and the organic molecules and hydrogen bonding interactions between anions of the ionic liquid and the organic compounds. [ABSTRACT FROM AUTHOR]

Pd/C-[BMIm][BF 4 ] catalyst displayed high activity for acceptorless dehydrogenation of biomass-derived alcohols to produce aromatic ketones under mild conditions without any acid/base additives, and this catalyst could be recovered and reused for 5 runs without obvious activity loss. This work provides a potential approach for the effective utilization of renewable biomass resources to produce aromatic compounds and clean H 2. [Display omitted] • The combination of Pd/C with specific ionic liquid of 1-butyl-3-methylimidazolium tetrafluoroborate ([BMIm][BF 4 ]) displayed high activity for the dehydrogenation of aromatic alcohols to produce aromatic ketones. • The Pd/C-[BMIm][BF 4 ] pair promoted the dehydrogenation of aromatic alcohols and inhabited the hydrogenation of aromatic alcohols. • The catalyst could be recycled for 5 runs without obvious loss of activity. • Pd/C could be anchored and stabilized by the IL through interacting with [BMIm]+ cation, and both the [BMIm]+ cation and the [BF 4 ]- anion play vital roles in activating hydroxyl-H and hydroxyl α-H of the aromatic alcohol. Acceptorless dehydrogenation of alcohols is a promising pathway for biomass resource utilization and hydrogen supply, but still lacking for simple and effective catalysts. Herein, we report a metal-ionic liquids (ILs) catalyst for synergistical catalytic dehydrogenation of aromatic alcohols to aromatic ketones under mild conditions without any acid/base additives. It is found that the combination of Pd/C with 1-butyl-3-methylimidazolium tetrafluoroborate ([BMIm][BF 4 ]) displays high activity for the dehydrogenation of biomass-derived alcohols including 1-phenyl-1-ethanol, 1-phenyl-1-propanol and 1-(4-methoxyphenyl)ethanol. Mechanistic studies reveal that the Pd/C can be anchored and stabilized by the IL via interacting with [BMIm]+ cation, and the [BF 4 ]- anion plays vital role in the activation of hydroxyl-H and α-H protons via hydrogen bonding interactions. These interactions create an effective microenvironmental for Pd/C catalyzing the cleavage of the hydroxyl-H and α-C H bonds of α-hydroxyl aromatic alcohols to generate aromatic ketones and H 2. Moreover, the Pd/C-[BMIm][BF 4 ] catalyst could be recovered and reused for 5 runs without obvious activity loss. This strategy provides more evidences for the synergetic catalysis of metal and ionic liquids and exhibits potential application prospects for hydrogen supply from renewable biomass-derived alcohols. [ABSTRACT FROM AUTHOR]

[Display omitted] • Metal chloride functionalized MOF-253(Al) was designed and prepared for NH 3 capture and separation. • NH 3 capture capacity of the optimal functionalized MOF is 3.33 times that of the pristine MOF. • Highly selective separation of NH 3 from NH 3 /N 2 /H 2 mixture was achieved. • The excellent performance is ascribed to NH 3 coordination toward Ni2+ and its hydrogen bonding with Cl− and carboxyl. Ammonia (NH 3) is produced from nitrogen (N 2) and hydrogen (H 2) by the Harber-Bosch process at high pressure and high temperature. Due to the reversibility and low conversion efficiency of the reaction, the product contains a large amount of raw gas, which seriously affects the production efficiency of ammonia. Therefore, it is essential to exploit high-performance adsorbents for separating NH 3 from NH 3 /N 2 /H 2 mixtures. Herein, we designed and synthesized a kind of metal–organic framework (MOF) composites by anchoring metal chloride (NiCl 2 , CoCl 2 , or SnCl 2) on the bipyridinium groups in the MOF-253(Al) pores. It is found that the optimal composite shows an NH 3 uptake capacity of 18.0 mmol/g at 25.0 °C and 1.0 bar, which is 3.33 times that of the pristine MOF-253(Al), and the composite exhibits a much faster adsorption kinetics of NH 3 than the pristine MOF-253(Al). Significantly, the excellent NH 3 uptake capacity at low pressure allows selective trapping of NH 3 from NH 3 /N 2 /H 2 at 25.0 °C with the selectivity coefficients of 5708 to N 2 and 2320 to H 2. Spectral measurements reveal that the synergistic action of NH 3 coordination to the metal in the MOF and the hydrogen bonding of NH 3 with both O atoms of the carboxyl groups and Cl− of the guest molecules account for such an excellent capture and selectivity. In general, the strategy developed here is simple and effective for improving the selectivity of NH 3 separation, which opens a new way for the design of high-performance solid adsorbents. [ABSTRACT FROM AUTHOR]

• A pore environment tailoring strategy for COFs was proposed to boost Pd(II) capture. • The adsorbent exhibited a high adsorption capacity for Pd(II) (532 mg/g). • Excellent selectivity, fast kinetics, and good reusability for Pd(II) recovery. • The remarkable performances depended on synergistic multiple interactions. Palladium is a rare resource, and its content in the earth's crust is very low. Thus, its selective recovery from a secondary source is of great importance but a challenging task. Herein, we have constructed a series of bipyridine-based two dimensional (2D) covalent organic frameworks (COFs) TFBBPY-COF, TFBBPY-OH-COF and TFBBPY-OMe-COF, and explored their extraction performance towards palladium in aqueous solutions. It is found that by tailoring the pore environment of these COFs, TFBBPY-OMe-COF shows a highly efficient adsorption and excellent selectivity for palladium recovery, and the maximum sorption capacity is up to 532 mg g−1, which is the highest value among the crystalline porous adsorbents reported up to now. Furthermore, TFBBPY-OMe-COF has been successfully employed to capture Pd(II) with a high selectivity (92.3%) in a simulated solution derived from a waste printed circuit boards. Spectral experiments and theoretical calculations reveal that the excellent adsorption of palladium is mainly attributed to the multiple hydrogen bonds of C–H---Cl and coordination of O and pyridine-N to Pd(II). [ABSTRACT FROM AUTHOR]

Abstract: In this work, the hydrogen bond formation ability of cation and anion of the ILs was determined by using the solvatochromic method and was found to be responsible for their catalytic activity in the Knoevenagel reactions. The enhancement in the hydrogen bond donor ability of the cations and the hydrogen bond acceptor ability of the anions can both lead to the increase in the catalytic activity of the ILs. From the proposed reaction mechanism, it was deduced that the cations of the ILs can form hydrogen bond with aldehyde to activate the C electrophile, and the anions of the ILs can promote active methylene compound to produce carboanion as nucleophile, showing dual function activation effect in the catalytic processes. In addition, the optimized N,N-dimethylethanolamnium acetate as dual function activator for the Koevenagel reactions benefits from wide substrates tolerance, ambient reaction temperature, easy work-up procedure, and easy reuse of the IL. [Copyright &y& Elsevier]

Abstract: In this work, aggregation behavior of [C12mim]Br in acetonitrile, ethylene glycol, N,N-dimethylformamide, formamide and dimethylsulfoxide solvents was investigated by conductivity and volume measurements. The critical aggregation concentration CAC, degree of anion binding β, and the standard Gibbs energy of aggregation ΔG o have been derived from the experimental data. Solvophobic parameters have been introduced to account for the interaction between alkyl chain of the IL and the solvents. It is shown that solvophobic effect and the hydrogen-bonding interaction between the IL anion and the solvents are the main factors affecting the aggregation of ILs in non-aqueous solvents. The aggregation of ILs in non-aqueous solvents can be controlled and regulated by solvent properties. [ABSTRACT FROM AUTHOR]

Abstract: Methyl orange (MO) exhibits a sensitive spectral signature to the polarity of medium environment. Using MO as the spectroscopic probe, this paper reports the results of studies on the aggregation of 1-alkyl-3-methylimidazolium-based ionic liquids (ILs, [C n mim]Br, n =8, 10, 12, and 16) in aqueous solutions. Along with the results obtained from the measurements of electrical conductivity and resonance light scattering (RLS), this investigation shows the characteristics of the IL aggregation and the properties of the bulk phase prior to the aggregation, and hence reveals the aggregation differences between surface active [C n mim]Br and traditional surfactants. It is shown that hydrogen bonds play a dominant role in the aggregation of ILs in addition to Coulombic and hydrophobic interactions. Compared with traditional cationic surfactant, IL displays the stronger aggregation due to the formation of the hydrogen bonded network. Also, such hydrogen bonded network results in the loose arrangements of imidazolium rings in the subaggregates of [C n mim]Br (n <10). When the mid-wavelength absorption band is just beginning to appear as the band of absorption maximum, the corresponding concentration is indicative of the formation of the perfect aggregates, and is in agreement with the critical aggregation concentration (CAC) of the ILs except [C8mim]Br. Moreover, it was found that the polarity in the core of the perfect IL aggregates is similar to the polarity within micelles of traditional cationic surfactant with the same alkyl chain length. [Copyright &y& Elsevier]