Improvement of biphasic polymerization by application of binary ionic liquid mixture

The mixture of two ionic liquids, 1-n-butyl-3-methylimidazolium and 1-(2-phenylethyl)-3-methylimidazolium chloroaluminates, [C₄-mim][AlCl₄] and [PhC₂-mim][AlCl₄], were applied as a medium to immobilize the Cp₂TiCl₂ titanocene catalyst for biphasic ionic liquid/hexane ethylene polymerization. The system makes possible to perform the reaction at lower temperatures, below the melting temperature of the aralkyl ionic liquid. A better separation of the ionic liquid phase was observed and an easier mass transfer of the polymer product from the ionic liquid to the hexane phase was obtained. The polyethylene reveals bimodal distribution of molecular weight. It is characterized by a high bulk density (500 g/dm³) and crystallinity degree (86%). The recycling of the ionic liquid medium containing the catalyst activated by AlEtCl₂, results in the highest yield obtained in such systems (550 kg PE(mol Ti)⁻¹).     

Novel ionic liquids as reaction medium for ATRP of acrylonitrile in the absence of any ligand

Atom transfer radical polymerization (ATRP) of acrylonitrile (AN) with ethyl 2-bromoisobutyrate (EBiB) as the initiator was firstly approached in the absence of any ligand in three novel ionic liquids, 1-methylimidazolium acetate ([mim][AT]), 1-methylimidazolium valerate ([mim][VT]) and 1-methylimidazolium caproate ([mim][CT]), respectively. All the polymerizations in the ionic liquids proceeded in a well-controlled manner. The polymerization in [mim][AT] not only showed the best control of molecular weight and its distribution but also provided a rather rapid reaction rate with the molar ratio of [AN]:[FeBr₂]:[EBiB] at 200:2:1. The resulting polyacrylonitrile was successfully used as the macroinitiator to proceed the chain extension polymerization in [mim][AT]. After simple purification, all the ionic liquids and FeBr₂ could be recycled and reused and had no effect on the living nature of polymerization.     

Reverse atom transfer radical polymerization of methyl methacrylate in imidazolium ionic liquids

Reverse atom transfer radical polymerization (ATRP) of methyl methacrylate (MMA) employing 2,2-azobisisobutyronitrile (AIBN)/CuCl₂/bipyridine(bipy) as the initiating system was approached at 80 °C in two ionic liquids, 1-butyl-3-methylimidazolium tetrafluoroborate ([C₄mim][BF₄]) and 1-dodecyl-3-methylimidazolium tetrafluoroborate ([C₁₂mim][BF₄]), respectively. The polymerization in [C₁₂mim][BF₄] proceeded in a well-controlled manner as evidenced by kinetic studies, end group analysis, chain extension, and block copolymerization results, but not in [C₄mim][BF₄] presumably due to poor solubility of PMMA in it. The kinetic study of reverse ATRP of MMA in recycled [C₁₂mim][BF₄] suggested that this ionic liquid could be re-used as reaction solvent after simple purification, without affecting the living nature of polymerization.     

Raman Microscopic Study of Japanese Beech (Fagus crenata) As Treated with the Ionic Liquid, 1-Ethyl-3-Methylimidazolium Chloride

The chemical changes in various morphological regions of Japanese beech (Fagus crenata) upon treatment with the ionic liquid 1-ethyl-3-methylimidazolium chloride ([C2mim][Cl]), which preferentially dissolves cellulose, have been investigated by Raman microscopy. The reactivity of polysaccharides and lignin with [C2mim][Cl] differed depending on the types of wood tissues. Chemical components in parenchyma cells showed higher resistance to degradation upon [C2mim][Cl] treatment than wood fiber and vessel. In addition, the lignin structure was partially degraded or modified by [C2mim][Cl] treatment, and its binding mode was complicated; nevertheless, lignin was stable in [C2mim][Cl].     

Improved activity and stability of pseudomonas capaci lipase in a novel biocompatible ionic liquid, 1‐isobutyl‐3‐methylimidazolium hexafluorophosphate

BACKGROUND: Enzymes may exhibit enhanced activity, stability and selectivity in ionic liquids, depending on the properties of the liquid. The physical–chemical properties of ionic liquids, however, may be modified by altering the anion or cation in the ionic liquid. This feature is a key factor for realizing successful reactions. In this work, a new ionic liquid, 1‐isobutyl‐3‐methylimidazolium hexafluorophosphate (abbreviated as [i‐C₄mim][PF₆]), was synthesized and investigated as a novel medium for the transesterification reaction of 2‐phenylethanol with vinyl acetate catalyzed by pseudomonas capaci lipase. As contrasts, the reaction was also carried out in two reference solvents; the isomeric ionic liquid [i‐C₄mim][PF₆], 1‐butyl‐3‐methylimidazolium hexafluorophosphate (abbreviated as [C₄mim][PF₆]), and hexanes. RESULTS: As reaction medium, [i‐C₄mim][PF₆] was best among the three solvents. The initial reaction rate, the equilibrium conversion of 2‐phenylethanol and the half‐lifetime of the lipase in [i‐C₄mim][PF₆] medium were about 1.5, 1.2 and 3‐fold that obtained in [C₄mim][PF₆] medium, respectively. The lipase in [i‐C₄mim][PF₆] medium was recycled 10 times without substantial diminution in activity. CONCLUSION: The ionic liquid [i‐C₄mim][PF₆] has good biocompatibility, and can be used widely as green media in various biocatalysis reactions to improve the activity and stability of enzymes. Besides hydrophobicity and nucleophilicity, the spatial configuration of ionic liquids is also considered a key factor effecting the behaviour of the enzyme in ionic liquids. Copyright © 2008 Society of Chemical Industry     

Aggregation Behavior of Imidazolium-Based Amino Acid Ionic Liquid Surfactants in Aqueous Solution: The Effect of Amino Acid Counterions

Three kinds of imidazolium-based amino acid ionic liquid surfactants (AAILS), 1-tetradecyl-3-methylimidazolium _L-aminopropionic acid salt ([C₁₄mim][Ala]), 1-tetradecyl-3-methylimidazolium _L-2-pyrrolidinecarboxylic acid salt ([C₁₄mim][Pro]), and 1-tetradecyl-3-methylimidazolium _L-aminohydrocinnamic acid salt ([C₁₄mim][Phe]), were synthesized by employing natural amino acids as counterions. Their adsorption and self-aggregation behaviors in aqueous solution were investigated systematically by means of surface tension and electrical conductivity measurements. Surface tension results indicate that surface properties and micellization behavior of AAILS are significantly affected by counterions. The micellization of [C₁₄mim][Pro] and [C₁₄mim][Phe] is entropy-driven at low temperatures but enthalpy-driven at high temperatures, whereas [C₁₄mim][Ala] is enthalpy-driven throughout the whole temperature range, owing to the variation in hydrophobicity and size of amino acid counterions. The surface activity of [C₁₄mim][Phe] is superior to that of conventional imidazolium-based ionic liquid surfactants with the same hydrocarbon chain length, 1-tetradecyl-3-methylimidazolium bromide (C₁₄mimBr), indicating that the aromatic counterion can promote the micellar formation process.     

乙腈+[C4mim][Cl]、乙腈+[C4mim][BF4]、乙腈+[C6mim][Cl]的气液平衡测定与关联（英文）

Vapor pressures were measured for acetonitrile+1-butyl-3-methylimidazolium chloride ([C4mim][Cl]),+1-butyl-3-methylimidazolium tetrafluoroborate ([C4mim][BF4]) and+1-hexyl-3-methylimidazolium chloride ([C6mim][Cl]) at temperatures of 313 to 353 K by a quasi-static method. The experimental data for the binary sys-tems were correlated by the non-random two liquid (NRTL) equation with an average absolute relative deviation (AARD) of within 1.84%. The results indicate that the three ionic liquids (ILs) can result in a negative deviation from the Raoult's law for the binary solutions containing acetonitrile, and the affinity between ILs and acetonitrile mole-cules fol ows the order [C4mim][BF4]+acetonitrile N [C4mim][Cl]+acetonitrile N [C6mim][Cl]+acetonitrile.     

Electrical conductivities for four ternary electrolyte aqueous solutions with one or two ionic liquid components at ambient temperatures and pressure

Thiswork provides amethod to explore the transport property of the electrolyte aqueous solutionswith one or two ionic liquids, especially focus on their electrical conductivity. The conductivities were measured for the ternary systems NaCl–[C₆mim][Cl] (1-hexyl-3-methylimidazolium chloride)–H₂O, [C₆mim][BF₄]–[C₆mim][Cl]–H₂O, NaNO₃–[C₆mim][BF₄](1-hexyl-3-methylimidazolium tetrafluoroborate)–H₂O, and [C₄mim][BF₄] (1-butyl-3- methylimidazolium tetrafluoroborate)–[C₆mim][BF₄]–H₂O, and their binary subsystems NaNO₃–H₂O, NaCl–H₂O, [C₆mim][BF₄]–H₂O, [C₆mim][Cl]–H₂O, and [C₄mim][BF₄]–H₂O, respectively. The conductivities of the ternary systems were also determined using generalized Young's rule and semi-ideal solution theory in terms of the data of their binary solutions. The comparison showed that the two simple equations provide good predictions for conductivity of mixed electrolyte solutions and the mixed ionic liquid solutions based on the conductivity of their binary subsystems.     

Extraction of dioxouranium(VI) in small channels using ionic liquids

The extraction behaviour of dioxouranium(VI) from nitric acid solutions with tributylphosphate (TBP) dissolved (30%, v/v) in room temperature ionic liquids (viz. 1-butyl-3-methylimidazolium bis{(trifluoromethyl)sulfonyl}amide, [C₄mim][NTf₂], 1-decyl-3-methylimidazolium bis{(trifluoromethyl)sulfonyl}amide, [C₁₀mim][NTf₂], and trihexyltetradecylphosphonium bis{(trifluoromethyl)sulfonyl}amide, [P_6 6 6 14][NTf₂]) was investigated. The experiments were performed in a capillary (0.5 mm internal diameter) made of Teflon, operated in the plug flow regime. The effects of ionic liquid type, initial nitric acid concentration, and residence time on dioxouranium(VI) extraction were studied. UV–vis spectroscopy was used for the determination of the dioxouranium(VI) concentration in the ionic liquid phase. For increasing [HNO₃]_aq,init, the %extraction decreased and then increased for [C₄mim][NTf₂], while for the other two ionic liquids it increased. The %extraction also increased with residence time in the channel. Overall mass transfer coefficients were about 0.2 s^–1 in all TBP/ionic liquid systems at the initial nitric acid concentration of 3 M when a 10 cm capillary was used.     

Theoretical and experimental investigation of CO2 solubility in nanofluids containing NaP zeolite nanocrystals and [C12mim][Cl] ionic liquid

Today, CO₂ separation is very important, both as an environmental issue and also in various industries. In this study, the water-based nanofluid of NaP zeolite nanocrystals and 1-dodecyl-3-methylimidazolium chloride ([C₁₂mim][Cl]) ionic liquid were mixed and tested experimentally for CO₂ absorption in an isothermal high pressure cell equipped with magnetic stirring. Zeolite nanocrystals were synthesized via the hydrothermal approach and characterized. A series of experiments were performed at different conditions to investigate the impact of various parameters, including nanoparticle type, nanoparticle concentration, stabilizer concentration, and the vessel's initial pressure, on CO₂ solubility. It was found that 0.02 wt.% of zeolite nanoparticles, 0.4 wt.% of [C₁₂mim][Cl] ionic liquid, and 0.05 wt.% of sodium dodecyl benzene sulphonate (SDBS) in nanofluids result in higher absorption of CO₂ compared to other concentrations. Furthermore, CO₂ absorption was increased by increasing ionic liquid and surfactant concentration up to a certain value near critical micelle concentration, but after that the CO₂ absorption was decreased. The overall CO₂ absorption enhancement at 20 bar for 0.02 wt.% zeolite and ZnO water-based nanofluids with 0.4% [C₁₂mim][Cl] ionic liquid and 0.02 wt.% SDBS were 26.9%, 21.5%, 21.2%, and 17% in comparison to pure water, respectively. In an absorption process using nanofluids, besides the influence of the mentioned parameters, the micro-convection caused by Brownian motion and the grazing effect of nanoparticles should be noted. Considering the micro-convection and grazing effects, a theoretical model should take into account the Brownian motion and grazing effects on the mass transfer rate in nanofluids to investigate the absorption enhancement by nano-particles.     

Acylation of salicylamide to 5-acetylsalicylamide using ionic liquids as dual catalyst and solvent

The Lewis acidic ionic liquids, 1-butyl-3-methylimidazolium chloroaluminate ([BMIM]Cl-nAlCl₃) and N-butylpyridinium chloroaluminate ([BPy]Cl-nAlCl₃), were used as both catalyst and solvent in Friedel–Crafts acylation of salicylamide with acetyl chloride to 5-acetylsalicylamide. The Lewis acidic ionic liquids, substituting for the conventional carcinogenic nitrobenzene solvent and anhydrous AlCl₃ catalyst, showed excellent catalytic activity in the acylation of salicylamide to 5-acetylsalicylamide. When [BMIM]Cl-2AlCl₃ was used as the catalyst, the yield of 5-acetylsalicylamide reached 81.3%. When [BPy]-2AlCl₃ was used as the catalyst, the maximum yield of 5-acetylsalicylamide was 89.2%. The content of AlCl₃ and the structure of the cations in the ionic liquids had synergistic effect on the acylation reaction.     

Solubility of CO2 in three cellulose-dissolving ionic liquids

The solubility of CO₂ in three cellulose-dissolving ionic liquids (1-ethyl-3-methylimidazolium diethylphosphate, [Emim][DEP], 1-allyl-3-methylimidazolium chloride, [Amim][Cl], and 1-butyl-3-methylimidazolium chloride, [Bmim][Cl]) at temperatures within 298 and 356 K and pressures up to 6.5 MPa was determined using a Van Ness-type apparatus (static isochoric). It was demonstrated that this device can work in isothermal and isoplethal modes, being the latter faster and more precise. Moreover, it was possible to determine CO₂ solubilities in metastable liquid [Bmim][Cl]. Experimental data were modeled using the Extended Henry's law correlation and the group contribution equation of state. New parameters for the binary interaction of CO₂ with ionic liquid groups were calculated.     

Direct synthesis of fibrous high molecular weight polyethylene using vanadium catalysts supported on an SiO2 ionic liquid system

Polyethylene of fibrous morphology was obtained using Cp₂VCl₂ and VCl₂(salenCl₂) catalysts activated by AlEt₂Cl and AlEtCl₂ and heterogenized on a supported ionic liquid system prepared with SiO₂ and 1‐(3‐triethoxysilyl)propyl‐3‐methylimidazolium chloroaluminate. The fibre length ranges from 15 to 60 µm, depending on the reaction conditions. The polyethylene is characterized by a high molecular weight ((1.1–2.4) × 10⁶ g mol^?1) and a narrow molecular weight distribution (1.4–2.5). It is a linear polymer, properly without branching. The DSC method reveals characteristic changes in melting temperature and crystallinity degree between the first and second scan heating cycles (141 °C and 136 °C, 71% and 46%, respectively). The wide angle X‐ray spectroscopy and Fourier transform infrared spectroscopy methods give crystallinity degree values of 40% and 41%–51%. The influence of type of catalyst precursor, alkylaluminium activator, catalyst/activator molar ratio, reaction time and temperature is discussed. © 2015 Society of Chemical Industry     

Polymerization of propylene with TiCl3–AlEt2Cl–trilauryltrithiophosphite catalyst

AlEt₃Cl was modified with TLTTP (trilauryltrithiophosphite) in the catalyst system consisting of TiCl₃ and AlEt₂Cl. The effects of TLTTP on the polymerization of propylene were studied in comparison with those of alkyl homologues of TLTTP. The catalytic behavior of the TiCl₃–AlEt₂Cl-TLTTP catalyst system in the polymerization of propylene was also studied in comparison with that of the TiCl₃–AlEt₂Cl catalyst system. In the study of the effect of various alkylthiophosphites added, it is found that the bulkiness of the alkyl group affects the rate of propylene polymerization and the stereoregularity of the resultant polymers. The TiCl₃–AlEt₂Cl–TLTTP catalyst system gave different catalytic behavior in the propylene polymerization from that of the unmodified conventional catalyst system (TiCl₃–AlEt₂Cl). These effects of TLTTP were considered to be due to the bulkiness of the alkyl groups attached to the phosphorous atom and the higher reactivity to TiCl₃ of the modified AlEt₂Cl than of the unmodified AlEt₂Cl.     

离子液体复合催化剂催化松节油聚合反应的研究

用三氯化铝、三氯化锑与卤化1-烷基-3-甲基咪唑盐〔[Cnm im]X〕制备了3种酸性离子液体复合催化剂{[C2m im]B r-A lC l3/SbC l3、[C4m im]C l-A lC l3/SbC l3和[C8m im]C l-A lC l3/SbC l3},并用于催化松节油聚合反应,结果表明,以[C4m im]C l-A lC l3/SbC l3的催化活性为佳。以[C4m im]C l-A lC l3/SbC l3为催化剂,考察了m(松节油)∶m(甲苯)∶m{[C4m im]C l}∶m(A lC l3)∶m(SbC l3),反应温度和反应时间等条件对反应结果的影响。在m(松节油)∶m(甲苯)∶m{[C4m im]C l}∶m(A lC l3)∶m(SbC l3)=15∶15∶2∶3∶1.5,反应温度-10℃,反应时间4~5 h较佳工艺条件下,固体树脂产物的收率为64%,软化点为104℃。     

Preparation of high energy fuel JP-10 by acidity-adjustable chloroaluminate ionic liquid catalyst

The isomerization of endo-tetrahydrodicyclopentadiene (endo-THDCPD) to its exo-isomer (JP-10) has been investigated by using chloroaluminate ionic liquids (ILs) as catalysts. The catalyst activity and selectivity could be optimized by varying the mole fraction of AlCl₃ in the IL. Undesirable by-products derived from side-reactions such as skeletal rearrangement, alkylation, cracking, and dimerization could be minimized by appropriate catalyst design and adjustment of the reaction conditions. The catalyst system was further optimized by selecting 1-butyl-3-methylimidazolium chloride as the basic IL and adding 0.60-0.65 mole fraction of AlCl₃ as the promoter. Using the optimized catalyst system, the isomerization of endo-THDCPD to exo-THDCPD proceeded at a fast rate at 50 °C with 98.9% conversion and 100% selectivity. The catalyst longevity has been demonstrated by recycling the IL several times without a noticeable reduction in catalytic activity.     

Deep removal of sulfur from real diesel by catalytic oxidation with halogen-free ionic liquid

A halogen-free task-specific ionic liquid (TSIL) of 1-(2-carboxylic acid) ethyl-3-methylimidazolium bisulfate ([(CH₂)₂COOHmim] [HSO₄]) is applied for deep oxidative desulfurization of real diesel as a catalyst and reaction media. The sulfur level of real diesel can be reduced from 200 to 20.5 μg/g at room temperature with small amount of ionic liquid using H₂O₂ as an oxidant. The used ionic liquid can be easily recycled and no obvious decrease in catalytic activity can be found after recycling five times.     

Inversion of stereoselectivity in 1,3-butadiene polymerization with a niobium catalyst induced by a change in the solvent system

Summary Catalytic 1,3-butadiene polymerization systems can be obtained with the new complex [NbO(C₁₆H₁₁O₆ ⁻)(C₂O₄ ²⁻)] as a catalyst. When the catalysis occurs in a homogeneous medium (toluene as a solvent) in conjunction with AlEt₂Cl, cis-1,4-polybutadiene is obtained. A remarkable inversion of stereoselectivity has been observed when the catalysis is carried out in a two phase system with the molten salt AlCl₃.1-methyl-3-n-butyl-imidazolium chloride (MBIC) as a solvent and AlEt₂Cl as a cocatalyst, giving the trans 1,4-polybutadiene. Received: 30 March 1998/Revised version: 25 May 1998/Accepted: 10 June 1998     

Soluble neodymium chloride 2-ethylhexanol complex as a highly active catalyst for controlled isoprene polymerization

Soluble NdCl₃·3EHOH (2-ethyl hexanol) in hexane combined with AlEt₃ is highly active for isoprene polymerization in hexane. The NdCl₃·3EHOH/AlEt₃ has higher activity than the typical binary catalyst NdCl₃·3ⁱPrOH (isopropanol)/AlEt₃ and ternary catalyst NdV₃ (neodymium versatate)/AlEt₂Cl/Al(i-Bu)₂H. The molecular weight of polyisoprenes can be controlled by variation of [Nd], [Al]/[Nd] ratio and polymerization temperature and time. The NdCl₃·3EHOH/AlEt₃ catalyst polymerized isoprene to afford products featuring high cis-1,4 stereospecificity (ca. 96%), high molecular weight (ca. 10⁵) and relatively narrow molecular weight distributions (M_w/M_n = 2.0-2.8) simultaneously. More importantly, some living polymerization characteristics were demonstrated: (a) absence of chain termination; (b) linear correlation between M_n and polymer yield; (c) increment of molecular weight in the ‘seeding’ polymerization. Though some deviation from the typical living polymerization such as molecular weight distribution is not narrow enough and the line of M_n and polymer yield does not extrapolate to zero, controlled polymerization with the current catalyst can still be concluded.     

Reverse atom transfer radical polymerization of MMA via immobilized catalysts in imidazolium ionic liquids

Reverse atom transfer radical polymerization (RATRP) of methyl methacrylate (MMA) employing immobilized catalyst was approached at 50 and 60°C in [C₈mim]PF₆, and compared with the polymerization of MMA DMF as solvent. Other ionic liquids, [C₆mim]BF₄, [C₈mim]BF₄, and [C₁₂mim]BF₄, were used as solvents to perform the RATRP of MMA. By comparison, we found that the [C₈mim]PF₆ was the best solvent in this immobilized catalyst system and the polymerization was best controlled. In addition, the immobilized catalyst spherules can easily separate from the reaction mixture, which avoids the prevalent problem of the catalyst residual in RATRP and also gives us a possibility to recycle the catalyst system. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 103: 3915–3919, 2007