Solubility of selected dibasic carboxylic acids in water,in ionic liquid of [Bmim][BF4], and in aqueous [Bmim][BF4] solutions

The solubilities of three dibasic carboxylic acids (adipic acid, glutaric acid, and succinic acid) in water, in the ionic liquid of 1-butyl-3-methyl-imidazolim tetrafluoroborate ([Bmim][BF₄]), and in the aqueous [Bmim][BF₄] solutions have been measured by a solid-disapperance method. The binodal curve of water + [Bmim][BF₄] was also determined experimentally from solid–liquid–liquid coexistence temperature up to near the upper critical solution temperature. Experimental results showed that each acid-containing binary behaved as a simple eutectic system. The solid–liquid equilibrium (SLE) data were correlated with the NRTL model for each binary system. The NRTL model with these determined binary parameters predicted the solid-disappearance temperatures of the aqueous ternary mixtures containing [Bmim][BF₄] and the dibasic acids to within an average absolute deviation of 2.0%.     

Ionic‐Liquid‐Based Synthesis of the Bromine‐Rich Bromidoplatinates [NBu3Me]2[Pt2Br10](Br2)2 and [NBu3Me]2[Pt2Br10](Br2)3

The bromine‐rich bromidoplatinates(IV) [NBu₃Me]₂[Pt₂Br₁₀](Br₂)₂ ( 1 ) and [NBu₃Me]₂[Pt₂Br₁₀](Br₂)₃ ( 2 ) were prepared by reaction of PtBr₄ and elemental bromine in the ionic liquid [MeBu₃N][N(Tf)₂] [N(Tf)₂ = bis(trifluoromethylsulfonyl)amide]. Both bromine‐rich bromidoplatinates(IV) contain [Pt₂Br₁₀]^2– anions and [NBu₃Me]⁺ cations as voluminous building units with an almost identical structural arrangement and very similar unit cells. The difference of the title compounds is related to the specific number of Br₂ molecules that link the [Pt₂Br₁₀]^2– anions to three‐dimensional networks. Whereas 1 is relatively stable under inert conditions, 2 releases bromine even at ambient pressure. The title compounds are characterized by single‐crystal structure analysis and Raman spectroscopy.     

Ionic liquids as porogens in the microwave-assisted synthesis of methacrylate monoliths for chromatographic application

Several imidazolium-based ionic liquids (ILs) with varying cation alkyl chain length (C₄–C₁₀) and anion type (tetrafluoroborate ([BF₄]⁻), hexafluorophosphate ([PF₆]⁻) and bis(trifluoromethylsulfonyl)imide ([Tf₂N]⁻)) were used as reaction media in the microwave polymerization of methacrylate-based stationary phases. Scanning electron micrographs and backpressures of poly(butyl methacrylate-ethylene dimethacrylate) (poly(BMA-EDMA)) monoliths synthesized in the presence of these ionic liquids demonstrated that porosity and permeability decreased when cation alkyl chain length and anion hydrophobicity were increased. Performance of these monoliths was assessed for their ability to separate parabens by capillary electrochromatography (CEC). Intra-batch precision (n = 3 columns) for retention time and peak area ranged was 0.80–1.13% and 3.71–4.58%, respectively. In addition, a good repeatability of RSD_{Retention time} = <0.30% and ∼1.0%, RSD_{Peak area} = <1.30% and <4.3%, and RSD_Efficiency = <0.6% and <11.5% for intra-day and inter-day, respectively exemplify monolith performance reliability for poly(BMA-EDMA) fabricated using 1-hexyl-3-methylimidazolium tetrafluoroborate ([C₆mim][BF₄]) porogen. This monolith was also tested for its potential in nanoLC to separate protein digests in gradient mode. ILs as porogens also fabricated different alkyl methacrylate (AMA) (C4–C18) monoliths. Furthermore, employing binary IL porogen mixture such as 1-butyl-3-methylimidazolium tetrafluoroborate ([C₄mim][BF₄]) and 1-butyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide ([C₄mim][Tf₂N]) successfully decreased the denseness of the monolith, than when using [C₄mim][Tf₂N] IL alone, enabling a chromatographic run to be performed with 1:1 ratio produced baseline separation for the analytes. The combination of ILs and microwave irradiation made polymer synthesis very fast (∼10 min), entirely green (organic solvent-free) and energy saving process.     

Solubility of H2S in ionic liquids [hmim][PF6], [hmim][BF4], and [hmim][Tf2N]

The solubility of hydrogen sulphide in three ionic liquids, viz. 1-hexyl-3-methylilmidazolium hexafluorophosphate ([hmim][PF₆]), 1-hexyl-3-methylimidazolium tetrafluoroborate ([hmim][BF₄]), and 1-hexyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide ([hmim][Tf₂N]), at temperatures ranging from 303.15 K to 343.15 K and pressures up to 1.1 MPa were determined. The solubility values were correlated using the Krichevsky–Kasarnovsky equation and Henry’s constants were obtained at different temperatures. Partial molar thermodynamic functions of solvation such as standard Gibbs free energy, enthalpy, and entropy were calculated from the solubility results. Comparison of the values obtained show that the solubility of H₂S in these three ionic liquids was in the sequence: [hmim][BF₄] > [hmim][PF₆] ≈ [hmim][Tf₂N].     

CMPO/[Cnmim][NTf2]体系对Eu3+和UO22+的萃取行为

讨论了辛基(苯基)-N,N-二异丁基胺甲酰基甲基氧化膦(CMPO)/1-烷基-3-甲基咪唑双(三氟甲烷磺酰)亚胺盐([C_nmim][NTf₂],n=2,8,12)萃取体系分别对硝酸溶液中的铕离子(Eu³⁺)和铀酰根离子(UO₂²⁺)的萃取行为。主要研究了硝酸浓度、接触时间、温度、CMPO浓度对CMPO/[C_nmim][NTf₂]体系萃取性能的影响,并选取CMPO/[C2mim][NTf₂]体系对模拟高放废液中的镧锕元素进行了萃取分离。结果表明:随着离子液体侧链长度增长,萃取平衡时间逐渐延长;CMPO/[C2mim][NTf₂]体系对Eu³⁺的萃取是放热反应,萃取率随酸度增加而逐渐降低,对UO₂²⁺则是吸热反应,萃取率随酸度增加而逐渐升高;通过机理研究,推测出对Eu³⁺的萃取反应是离子交换,而对UO₂²⁺的萃取反应则是中性配位;CMPO/[C2mim][NTf₂]体系能有效的萃取模拟高放废液中的镧系、锕系元素,且在高酸下有一定的镧锕分离效果。     

Solubility of H2S in 1-(2-hydroxyethyl)-3-methylimidazolium ionic liquids with different anions

The solubility of hydrogen sulfide in a series of 1-(2-hydroxyethyl)-3-methylimidazolium ([HOemim]⁺)-based ionic liquids (ILs) containing different anions, viz. hexafluorophosphate ([PF₆]⁻), trifluoromethanesulfonate ([OTf]⁻), and bis-(trifluoromethyl)sulfonylimide ([Tf₂N]⁻) at temperatures ranging from 303.15 to 353.15 K and pressures of up to about 1.8 MPa was measured by a volumetric based static apparatus. The solubility data were correlated using two models: (1) the Krichevsky–Kasarnovsky equation and (2) the extended Henry's law combined with the Pitzer's virial expansion for the excess Gibbs energy. Henry's law constants (at zero pressure) in mole-fraction and molality scales were obtained at different temperatures by means of these two models. Using the solubility data, the partial molar thermodynamic functions of solution, i.e. Gibbs energy, enthalpy, and entropy were calculated. Comparison showed that the solubility of H₂S is greater than that of CO₂ in the corresponding ILs studied in this work and that the solubility of both gases increases as the number of trifluoromethyl (–CF₃) groups in the anion increases, i.e. the solubility behavior of both gases follows the order [HOemim][Tf₂N] ≥ [HOemim][OTf] > [HOemim][PF₆] > [HOemim][BF₄].     

Speciation of Rare‐Earth Metal Complexes in Ionic Liquids: A Multiple‐Technique Approach

The dissolution process of metal complexes in ionic liquids was investigated by a multiple‐technique approach to reveal the solvate species of the metal in solution. The task‐specific ionic liquid betainium bis(trifluoromethylsulfonyl)imide ([Hbet][Tf₂N]) is able to dissolve stoichiometric amounts of the oxides of the rare‐earth elements. The crystal structures of the compounds [Eu₂(bet)₈(H₂O)₄][Tf₂N]₆, [Eu₂(bet)₈(H₂O)₂][Tf₂N]₆?2H₂O, and [Y₂(bet)₆(H₂O)₄][Tf₂N]₆ were found to consist of dimers. These rare‐earth complexes are well soluble in the ionic liquids [Hbet][Tf₂N] and [C₄mim][Tf₂N] (C₄mim=1‐butyl‐3‐methylimidazolium). The speciation of the metal complexes after dissolution in these ionic liquids was investigated by luminescence spectroscopy, ¹H, ¹³C, and ⁸⁹Y NMR spectroscopy, and by the synchrotron techniques EXAFS (extended X‐ray absorption fine structure) and HEXS (high‐energy X‐ray scattering). The combination of these complementary analytical techniques reveals that the cationic dimers decompose into monomers after dissolution of the complexes in the ionic liquids. Deeper insight into the solution processes of metal compounds is desirable for applications of ionic liquids in the field of electrochemistry, catalysis, and materials chemistry.     

Synthesis of fused tetrahydro-β-carbolinequinoxalinones in 1-n-butyl-2,3-dimethylimidazolium bis(trifluoromethylsulfonyl)imide ([bdmim][Tf2N]) and 1-n-butyl-2,3-dimethylimidazolium perfluorobutylsulfonate ([bdmim][PFBuSO3]) ionic liquids

Starting from tryptophan methyl ester, a three-step synthesis of fused tetrahydro-β-carbolinequinoxalinones in two new ionic liquids, [bdmim][Tf₂N] and [bdmim][PFBuSO₃], was described. Both ionic liquids can be readily prepared from commercially available starting materials in high yields. Unlike the commonly used [PF₆]-based ionic liquids that evidently undergo slow hydrolysis of the PF₆ anion with the concomitant release of HF, ionic liquids of [bdmim][Tf₂N] and [bdmim][PFBuSO₃] are not only chemically stable but also apparently inert to hydrolysis and therefore organic reactions carried out in both ionic liquids proceed smoothly with good yields. The overall isolated yields for this three-step synthesis of tetrahydro-β-carbolinequinoxalinones were 34-55%. To the best of our knowledge, the preparation of fused tetrahydro-β-carbolinequinoxalinones was unprecedented.     

Formation of metastable crystals of [C4mim][NTf2] and [C6mim][NTf2]

Heat capacities of crystalline 1-butyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide [C₄mim][NTf₂] and 1-hexyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide [C₆mim][NTf₂] in the range 80 K-T_fus were measured in an adiabatic calorimeter. Anomalies in the heat-capacity curves for the both compounds occurred near 240 K. Positions of the anomalies depended on thermal history of the samples. More stable crystals had higher heat capacities in the range 220-260 K. Below 200 K heat capacities of all the crystals of the same compound were indistinguishable.     

Phase behaviour of 1-hexyloxymethyl-3-methyl-imidazolium and 1,3-dihexyloxymethyl-imidazolium based ionic liquids with alcohols,water, ketones and hydrocarbons: The effect of cation and anion on solubility

The liquid–liquid equilibrium (LLE), or solid–liquid equilibrium (SLE) of more than 20 binary systems containing 1-hexyloxymethyl-3-methyl-imidazolium bis(trifluoromethylsulfonyl)-imide [C₆H₁₃OCH₂MIM][Tf₂N] with alcohol (butan-1-ol, or hexan-1-ol, or octan-1-ol), water and ketone (3-pentanone, or cyclopentanone) and of 1-hexyloxymethyl-3-methyl-imidazolium tetrafluoroborate [C₆H₁₃OCH₂MIM][BF₄] with alcohol (methanol, or ethanol, or butan-1-ol, or hexan-1-ol, or octan-1-ol), water and ketone (3-pentanone, or cyclopentanone) have been measured. The solubility of dialkoxy-imidazolium salts: (1) 1,3-dihexyloxymethyl-imidazolium bis(trifluoromethylsulfonyl)-imide [(C₆H₁₃OCH₂)₂IM][Tf₂N] in alcohol (butan-1-ol, or hexan-1-ol, or octan-1-ol, or decan-1-ol), in water and hydrocarbon (benzene, hexane and cyclohexane); (2) 1,3-dihexyloxymethyl-imidazolium tetrafluoroborate [(C₆H₁₃OCH₂)₂IM][BF₄] in alcohol (hexan-1-ol, or octan-1-ol, or decan-1-ol) and water have been measured. Measurements were carried out by using a dynamic method from T = 275 K to the boiling point of the solvent. In this work a systematic study of the impact of different factors on the phase behaviour of hexyloxy-imidazolium-based ionic liquids with polar and nonpolar solvents has been presented. Most of the examined systems showed immiscibility in the liquid phase with an upper critical solution temperature (UCST), or complete solubility of the ionic liquid at room temperature in many solvents. An increase in the alkyl chain length of alcohol resulted in an increase in the UCST. The choice of anion was shown to have large impact on the solubility: by changing the anion [Tf₂N]⁻ to [BF₄]⁻, the solubility dramatically decreased and the UCST increased. By contrast, increasing hydrogen bonding opportunities with the solvent by replacing a methyl group with the second alkoxy-group on the imidazolium ring results in an increase of the solubility.     

The metathesis reactions of [SNS][SbF6] and [SN][AsF6] with Li[Al(OC(CF3)3)4] in liquid SO2

The small di- and triatomic molecules [SN]⁺ and [SNS]⁺ have shown versatile chemistries and [SNS]⁺ is an important starting reagent for many sulfur-nitrogen radicals. However, their chemistry is limited to the more polar solvents (e.g. SO₂). In this work an attempt is made to increase their solubility in less polar solvents by exchange of the usual [MF₆]⁻ (M = As, Sb) anions by the large and weakly coordinating [Al(OC(CF₃)₃)₄]⁻. As expected the metathesis reactions of [SN][AsF₆] and [SNS][SbF₆] with Li[Al(OC(CF₃)₃)₄] in liquid sulfur dioxide resulted in the formation of the insoluble Li[SbF₆], which is the driving force for these metathesis reactions. The characterization of the compounds by IR and multinuclear NMR revealed that [SNS]⁺ formed a [Al(OC(CF₃)₃)₄]⁻ salt in a clean reaction. A preliminary crystal structure of [SNS][Al(OC(CF₃)₃)₄] is presented. The solubility of [SNS][Al(OC(CF₃)₃)₄] in CH₂Cl₂ is significantly increased with respect to the corresponding [MF₆]⁻ salts, and potentially opens up new areas of [SNS]⁺ chemistry. The reaction of the more reactive [SN]⁺ with Li[Al(OC(CF₃)₃)₄] was less clear. Multinuclear NMR and IR spectra were consistent with the formation of [SN][Al(OC(CF₃)₃)₄], which also showed significant decomposition.     

New open-framework in the uranyl vanadates A3(UO2)7(VO4)5O (A=Li, Ag) with intergrowth structure between A(UO2)4(VO4)3 and A2(UO2)3(VO4)2O

New uranyl vanadates A₃(UO₂)₇(VO₄)₅O (M=Li (1), Na (2), Ag (3)) have been synthesized by solid-state reaction and their structures determined from single-crystal X-ray diffraction data for 1 and 3. The tetragonal structure results of an alternation of two types of sheets denoted S for _∞²[UO₂(VO₄)₂]⁴⁻ and D for _∞²[(UO₂)₂(VO₄)₃]⁵⁻ built from UO₆ square bipyramids and connected through VO₄ tetrahedra to _∞¹[U(3)O₅-U(4)O₅]⁸⁻ infinite chains of edge-shared U(3)O₇ and U(4)O₇ pentagonal bipyramids alternatively parallel to a- and b-axis to construct a three-dimensional uranyl vanadate arrangement. It is noticeable that similar _∞[UO₅]⁴⁻ chains are connected only by S-type sheets in A₂(UO₂)₃(VO₄)₂O and by D-type sheets in A(UO₂)₄(VO₄)₃, thus A₃(UO₂)₇(VO₄)₅O appears as an intergrowth structure between the two previously reported series. The mobility of the monovalent ion in the mutually perpendicular channels created in the three-dimensional arrangement is correlated to the occupation rate of the sites and by the geometry of the different sites occupied by either Na, Ag or Li. Crystallographic data: 293 K, Bruker X8-APEX2 X-ray diffractometer equipped with a 4 K CCD detector, MoKα, λ=0.71073 Å, tetragonal symmetry, space group P4¯m2, Z=1, full-matrix least-squares refinement on the basis of F²; 1,a=7.2794(9) Å, c=14.514(4) Å, R1=0.021 and wR2=0.048 for 62 parameters with 782 independent reflections with I?2σ(I); 3, a=7.2373(3) Å, c=14.7973(15) Å, R1=0.041 and wR2=0.085 for 60 parameters with 1066 independent reflections with I?2σ(I).     

Mixing and decomposition behavior of {[4bmpy][Tf2N] + [emim][EtSO4]} and {[4bmpy][Tf2N] + [emim][TFES]} ionic liquid mixtures

Mixing ionic liquids (ILs) has been revealed as a useful way to finely tune the properties of IL-based solvents. The scarce available studies on IL mixtures have shown a quasi-ideal behavior of their physical properties. In this work, we have performed a thermophysical characterization of two binary IL mixtures, namely {4-methyl-N-butylpyridinium bis(trifluoromethylsulfonyl)imide ([4bmpy][Tf₂N]) + 1-ethyl-3-methylimidazolium ethylsulfate ([emim][EtSO₄])} and {[4bmpy][Tf₂N] + 1-ethyl-3-methylimidazolium 1,1,2,2-tetrafluoroethanesulfonate [emim][TFES]}. Both binary IL mixtures have been recently proposed as promising solvents in the (liquid + liquid) extraction of aromatic hydrocarbons from mixtures with alkanes. Densities, viscosities, refractive indices, thermal stability, and specific heats of the {[4bmpy][Tf₂N] + [emim][EtSO₄]} and {[4bmpy][Tf₂N] + [emim][TFES]} IL mixtures have been measured as a function of both temperature and composition. Dynamic viscosities, refractive indices, and thermal stability of the {[4bmpy][Tf₂N] + [emim][EtSO₄]} mixture have exhibited strong deviations from the ideality, in contrast with the quasi-ideal properties of the {[4bmpy][Tf₂N] + [emim][TFES]} mixture and the behavior of the imidazolium and pyridinium-based IL mixtures studied hitherto. The reliability of predictive methods of the thermophysical properties of the mixtures has also been evaluated.     

A hybrid material based on [Mo6Br14] inorganic cluster units and [BEDO-TTF] organic monocationic radicals: Synthesis, structure and properties of (BEDO-TTF)2Mo6Br14(PhCN)4

The first charge transfer salt based on non- dimerized [BEDO-TTF]⁺ monocationic radical (BEDO-TTF=bis(ethylenedioxy)tetrathiafulvalene) associated with [Mo₆Br₁₄]²⁻ cluster anions has been synthesized by conventional electro-oxidation and characterized by single crystal X-ray diffraction, UV-VIS-NIR absorption and magnetic susceptibility measurements. (BEDO-TTF)₂Mo₆Br₁₄(PhCN)₄ crystallizes in the monoclinic system, space group P2₁/n, a=10.414(4) Å, b=21.711(7) Å, c=15.958(5) Å, β=93.65(3)°, V=3601(2) Å³, Z=2, R₁=0.0578, wR₂=0.0731. The structure of this hybrid compound is built up from a [BEDO-TTF]⁺ and PhCN (benzonitrile) organic framework in which are hosted the [Mo₆Br₁₄]²⁻ inorganic cluster units. It results in non- dimerized [BEDO-TTF]⁺ cations that exhibit a paramagnetic behavior characteristic of one unpaired electron.     

Effects of temperature and anion species on CO2 permeability and CO2/N2 separation coefficient through ionic liquid membranes

The permeability of carbon dioxide (CO₂) through imidazolium-based ionic liquid membranes was measured by a sweep gas method. Six species of ionic liquids were studied in this work as follows: [emim][BF₄], [bmim][BF₄], [bmim][PF₆], [bmim][Tf₂N], [bmim][OTf], and [bmim][dca]. The ionic liquids were supported with a polyvinylidene fluoride porous membrane. The measurements were performed at T = (303.15 to 343.15) K. The partial pressure difference between feed and permeate sides was 0.121 MPa. The permeability of the CO₂ increases with temperature for the all ionic liquid species. Base on solution diffusion theory, it can be explained that the diffusion coefficient of CO₂ in an ionic liquid affects the temperature dependence more strongly than the solubility coefficient. The greatest permeability was obtained with the [bmim][Tf₂N] membrane. The membrane of [bmim][PF₆] presents the lowest permeability.The separation coefficient between CO₂ and N₂ through the ionic liquid membranes was also investigated at the volume fraction of CO₂ at feed side 0.10. The separation coefficient decreases with the increase of temperature for the all ionic liquid species. The membrane of [emim][BF₄] and [bmim][BF₄] gives the highest separation coefficient at constant temperature. The lowest separation coefficient was obtained from [bmim][Tf₂N] membrane which presents the highest permeability of CO₂.     

Synthesis, crystal structure, spectroscopic and thermal properties of [Et4N][Ta6Br12(H2O)6]Br4·4H2O (Et=ethyl)—A new compound with the paramagnetic [Ta6Br12] cluster core

A new hexanuclear cluster compound, [Et₄N][Ta₆Br₁₂(H₂O)₆]Br₄·4H₂O (Et=ethyl) (1), with the paramagnetic [Ta₆Br₁₂]³⁺ cluster entity, was synthesized and characterized by elemental and TG/DTA analyses, IR and UV/Vis spectroscopy and by a single-crystal X-ray diffraction study. The presence of the paramagnetic [Ta₆Br₁₂]³⁺ unit was confirmed also by the room-temperature magnetic and EPR measurements. The compound crystallizes in the tetragonal I4₁/a space group, with a=14.299(5), c=21.241(5) Å, Z=4, R₁(F)/wR₂(F²)=0.0296/0.0811. The structure contains discrete [Ta₆Br₁₂(H₂O)₆]³⁺ cations with an octahedron of metal atoms edge-bridged by bromine atoms and with water molecules occupying all six terminal positions. The cluster units are positioned in the vertices of the three-dimensional (pseudo)diamond lattice. The structure shows similarities with literature reported structures of cluster compounds crystallizing in the diamond space group.     

The reaction of copper(II) and 2-hydrazino-2-imidazoline leading to the in situ formation of bisimidazoline (biz). Crystal structure and vibrational spectroscopy of mixed-valence [Cu(biz)2][Cu2Br4] complex

The reaction of Cu(OH)₂ and 2-hydrazino-2-imidazoline hydrobromide surprisingly resulted in complex compound where Cu(II) ions are chelated by a new ligand, namely bisimidazoline (biz). As has been found in the X-ray analysis, the [Cu(biz)₂]²⁺ cations are accompanied by [Cu₂Br₄]²⁻ anions, which makes the whole compound of metal-mixed-valency type. Both ions are centrosymmetric and quasi-planar. The Cu(II) coordination environment is a rectangle with almost equal Cu–N bond lengths (1.984(3), 1.987(3) Å). The electrostatic interaction of both complex ions is strengthened by two strong N–H···Br and four weaker (C–H···Br, C–H···N) hydrogen bonds. The relatively simple IR and Raman spectra were interpreted with help of quantum calculations carried out at the B3LYP/LanL2DZ level. The characterization of computed normal vibrations and correlating observed bands is given in terms of approximate D_2h symmetry. The most intense band resulting from the Cu–N stretching vibration (B_3u) was located at 342 cm⁻¹, by ⁶³Cu and ⁶⁵Cu isotope substitution. The chemical reactions leading to the formation of presented compound are also proposed.     

Speciation of Aluminium in Mixtures of the Ionic Liquids [C3mpip][NTf2] and [C4mpyr][NTf2] with AlCl3: An Electrochemical and NMR Spectroscopy Study

This paper reports on the electrodeposition of aluminium on several substrates from the air‐ and water‐stable ionic liquids 1‐propyl‐1‐methylpiperidinium bis(trifluoromethylsulfonyl)amide ([C₃mpip][NTf₂]) and 1‐butyl‐1‐methylpyrrolidinium bis(trifluoromethylsulfonyl)amide ([C₄mpyr][NTf₂]), which contain anhydrous AlCl₃. At an AlCl₃ concentration of 0.75 molal, no evidence for aluminium electrodeposition was observed in either system at room temperature. However, aluminium electrodeposition becomes feasible upon heating the samples to 80 °C. Aluminium electrodeposition from bis(trifluoromethylsulfonyl)amide‐based ionic liquids that contain AlCl₃ has previously been shown to be very dependent upon the AlCl₃ concentration and has not been demonstrated at AlCl₃ concentrations below 1.13 molal. The dissolution of AlCl₃ in [C₃mpip][NTf₂] and [C₄mpyr][NTf₂] was studied by variable‐temperature ²⁷Al NMR spectroscopy to gain insights on the electroactive species responsible for aluminium electrodeposition. A similar change in the aluminium speciation with temperature was observed in both ionic liquids, thereby indicating that the chemistry was similar in both. The electrodeposition of aluminium was shown to coincide with the formation of an asymmetric four‐coordinate aluminium‐containing species with an ²⁷Al chemical shift of δ=94 and 92 ppm in the [C₃mpip][NTf₂]–AlCl₃ and [C₄mpyr][NTf₂]–AlCl₃ systems, respectively. It was concluded that the aluminium‐containing species that give rise to these resonances corresponds to the electroactive species and was assigned to [AlCl₃(NTf₂)]^?.     

Crystal and molecular structure of (NH4)2[UO2(NO3)4] and [(NH4)(18C6)]2[UO2(NO3)4]

Single crystals of diammonium tetranitratouranylate (NH₄)₂[UO₂(NO₃)₄] (I) and a new diammonium tetranitratouranylate complex with 18-crown-6 [(NH₄)(18C6)]₂[UO₂(NO₃)₄] (II) have been synthesized by the reaction of diaquadinitratouranyl tetrahydrate with ammonium nitrate in a nitric acid solution and the reaction of the same reagents with 18C6 in an ethanol solution, respectively. The X-ray diffraction analysis of compounds I and II has been performed. Crystals of compounds I and II are monoclinic, Z = 2, space group P2₁/n, a = 6.4075(5) ?, b = 7.7851(7) ?, c = 12.4461(12) ?, β = 101.239(1)°, V = 608. 94(9) ?³ for compound I and a = 10.542(9) ?, b = 8.590(8) ?, c = 22.5019(19) ?, β = 101.632(1)°, V = 2058.3(3) ?³ for compound II. The [UO₂(NO₃)₄]²⁻ complex anion in compounds I and II contains two monodentate and two bidentate cyclic nitrato groups, and the coordination number of uranyl is 6. The 18C6 molecule in the structure of compound II has the classic crown conformation and combined with the ammonium ion by three hydrogen bonds. Compounds I and II formed by electrostatic attraction forces between counterions are stabilized by (NH₄⁺)NH...O(NO₃⁻) interionic hydrogen bonds.     

Catalytic performance of [Bmim][Co(CO)4] functional ionic liquids for preparation of 1,3-propanediol by coupling of hydroesterification-hydrogenation from ethylene oxide

In this paper, synthesis of 1,3-propanediol (1,3-PDO) through coupling of hydroesterification-hydrogenation from ethylene oxide (EO) catalyzed by 1-butyl-3-methylimidazolium cobalt tetracarbonyl [Bmim][Co(CO)₄] functional ionic liquid which was prepared by metathesis reaction between [Bmim]Cl and KCo(CO)₄ has been studied. The structure of [Bmim][Co(CO)₄] was characterized by FT-IR and ¹H NMR. Using [Bmim][Co(CO)₄] as catalyst and [Bmim]PF₆ as solvent, 1,3-PDO was prepared for the first time by coupling of hydroesterifaction of EO and hydrogenation of methyl 3-hydroxypropionate (3-HPM). The yield of 3-HPM can reach 90.8%, while the yield of 1,3-PDO up to 82.9%. The catalyst can be separated from the product mixture by extraction with deionized water and recycled several times without significant loss of catalytic efficiency. A possible reaction mechanism has also been proposed.