Acoustic and Volumetric Properties of Diluted Solutions of Water in Ionic Liquids

Herein, we report the densities and speeds of sound in binary mixtures of three hydrophobic and one hydrophilic ionic liquids: 1-butyl-3-methylimidazolium bis[(trifluoromethyl)sulfonyl]imide, [C4mim][NTf2], 1-butyl-1-methylpyrrolidinium bis[(trifluoromethyl)sulfonyl]imide, [C4mpyr][NTf2], 1-propyl-3-methylimidazolium bis[(trifluoromethyl)sulfonyl]imide, [C3mim][NTf2] and 1-ethyl-3-methylimidazolium thiocyanate, [C2mim][SCN], with water at 298.15 K and 0.1 MPa. The concentration range of water, which encompassed relatively small values well below the saturation point, is often regarded as an impurity for hydrophobic ionic liquids. On the basis of experimental results the molar volume, adiabatic molar compressibility, partial molar volume and apparent molar volume, as well as, partial molar and apparent molar isentropic compressibility properties were then calculated. Interesting results are obtained using the solutions based on the hydrophilic [C2mim][SCN], since these mixtures are characterized by relatively low density and high values of speed of sound. Furthermore, the partial molar volumes and partial molar adiabatic compressibilities of water in solution with [C2mim][SCN] are the lowest among the investigated in mixtures with ionic liquids. However, in the case of the hydrophobic ionic liquid solutions, only small differences are observed for molar adiabatic compressibilities with the change of the cation structure, i.e. for water + [C4mim][NTf2] or + [C4mpyr][NTf2]. A more pronounced difference has been observed for the partial molar compressibility of water in solutions with these two ionic liquids.

Pro-fragrant ionic liquids with stable hemiacetal motifs: water-triggered release of fragrances

Stable liquid and solid salts in the form of elusive hemiacetals, appended with fragrant alcohols, have been synthesised as pro-fragrances, and the controlled release of these fragrances, triggered by water, is demonstrated

Dual functional ionic liquids as antimicrobials and plasticisers for medical grade PVCs

Two ionic liquids, 1-ethylpyridinium docusate (IL1) and tri-n-butyl(2-hydroxyethyl)phosphonium docusate (IL2), were designed and synthesized with the explicit intention of imparting a combination of plasticization and antimicrobial efficacy when incorporated into medical grade poly(vinyl chloride)s (PVCs). The glass transition (T-g) of PVC can be reduced by >20 degrees C on addition of 15 wt% IL2. Both IL1 and IL2 leached to varying extents from the base PVC resins rendering the surface of the PVCs hydrophilic. The antimicrobial activity of both ILs is related to the presence and concentration of both cationic and anionic component of the ILs leached from the PVC and inversely proportional to the extent of PVC gelation. Blends of the PVCs with IL1 displayed antibacterial activity against almost all Gram-positive bacteria tested, including coagulase-negative Staphylococci (CoNS) and methicillin-resistant Staphylococcus aureus (MRSA), but not with IL2 at low concentration in contrast to our previous study when high concentrations of IL2 were used. The more hydrophilic IL1 when added to PVC retards biofilm formation.

Low cycle fatigue properties of CLAM steel at room temperature

The low cycle fatigue (LCF) properties and the fracture behavior of China Low Activation Martensitic (CLAM) steel have been studied over a range of total strain amplitudes from 0.2 to 2.0%. The specimens were cycled using tension-compression loading under total strain amplitude control. The CLAM steel displayed initial hardening followed by continuous softening to failure at room temperature in air. The relationship between strain and fatigue life was predicted using the parameters obtained from fatigue test. The factors effecting on low cycle fatigue of CLAM steel consisted of initial state of matrix dislocation arrangement, magnitude of cyclic stress, magnitude of total strain amplitude and microstructure. The potential mechanisms controlling the stress response, cyclic strain resistance and low cycle fatigue life have been evaluated.

Naphthenic acid extraction and speciation from Doba crude oil using carbonate-based ionic liquids

A number of tetraalkylammonium methylcarbonate and hydrogencarbonate based ionic liquids are shown to be capable of reacting with the naphthenic acids contained in Doba crude oil via a neutralisation reaction. Spectral studies show that the ionic liquids neutralisation mechanism involves the formation of an ionic liquid-naphthenate complex, liberating methanol and carbon dioxide. Extraction of the neutralised complex into a separate methanol phase and subsequent regeneration using aqueous carbonic acid results in ∼70% of the ionic liquid being recovered for recycle. Isolation of the naphthenic acids shows that these make up to 0.85 wt% of the crude oil. Speciation of the naphthenic acids shows a mixture of monocyclic, through to tetracyclic structures with carbon numbers in the range C₁₂-C₄₀.

Olefin / Paraffin separation using Task-Specific Materials based on Ionic Liquids: Advances in Gas Processing

In this work, 1-hexene was extracted from its mixtures with n-hexane in varying ratios using a task specific ionic liquid. Herein, the ionic liquid (IL) 1-butyl-3-methylimidazolium nitrate, [BMIM][NO3], was used and examined with and without the addition of a metal salt. The impact of water on both selectivity and distribution coefficient was also tested. Four potential metal salts were investigated, the results of which demonstrate that the dissolution of transition-metal salts in the IL improves the separation of 1-hexene from n-hexane through metal-olefin complexation. Additionally, the presence of water in IL solutions containing metal salt enhances this selectivity. Finally, UNIFAC was used to correlate the experimental LLE data with good accuracy.

Dissolution and processing of cellulose using ionic liquids, cellulose solution, and regenerating cellulose.

Cellulose is dissolved in an ionic liq. without derivatization, and is regenerated in a range of structural forms without requiring the use of harmful or volatile org. solvents. Cellulose soly. and the soln. properties can be controlled by the selection of the ionic liq. constituents, with small cations and halide or pseudohalide anions favoring soln.; dissoln. can be aided by irradn. An ionic liq., [C4mim]Cl, proved to be the best for dissolving cellulose. [on SciFinder(R)]

Ionic liquids containing secondary hydroxyl-groups and a method for their preparation.

The invention provides ionic liqs., [R'1CH(OH)CH2]NR'nX (X = anion, R' = alkyl, alkenyl, alkynyl, cycloalkyl, alkylcarbonylalkyl, alkoxy, haloalkyl, haloalkoxy, alkenyloxy, alkynyloxy, cycloalkyloxy, aryl), having a secondary hydroxyl group, and an atom-efficient method for the prepn. of these ionic liqs., by epoxidn. of a protonated nitrogen- contg. org. base (which can optionally be prepd. in situ) in the presence of an anion suitable for supporting ionic liq. formation. Thus, reaction of 1-methylimidazole with HCl in EtOH ∼ 25° followed by treatment with propylene oxide gave 1-(2-hydroxypropyl)-3-methylimidazolium chloride. [on SciFinder(R)]

Polymer dissolution and blend formation in ionic liquids.

The ionic liqs. are for the dissoln. of various polymers and/or copolymers, the formation of resins and blends, and the reconstitution of polymer and/or copolymer solns., and the dissoln. and blending of functional additives and/or various polymers and/or copolymers. Thus, ≥1 ionic liq., which is a liq. salt complex that exists in the liq. phase between about -70 to 300°, is mixed with ≥2 differing polymeric materials to form a mixt., and adding a nonsolvent to the mixt. to remove the ionic liq. from the resin or blend. [on SciFinder(R)]