Effect of anion in carboxylate-based ionic liquids on catalytic activity of transesterification with vinyl esters and the solubility of cellulose.

The role of 1-ethyl-3-methylimidazolium (Emim) carboxylate-type ionic liquid (IL) as the solvent and organocatalyst for transesterification reaction of cellulose was investigated. The reported method using Emim acetate and vinyl ester caused an undesired side reaction: the acetate anion derived from EmimOAc was introduced into cellulose ester. To improve the reaction system, ILs with a high cellulose solubility, a high degree of substitution (DS) value, and low side-reaction were systematically explored.

Synthesis of zero-valent iron nanoparticles via laser ablation in a formate ionic liquid under atmospheric conditions.

Transition metal nanoparticles (NPs) are promising materials for use as catalysts in many processes, although they are easily oxidized under ambient conditions. In this communication, a novel synthetic method is proposed for producing zero-valent iron (Fe) NPs by laser ablation under atmospheric conditions using the reducing properties of a formate-based ionic liquid solvent. The valence state of Fe was confirmed using X-ray absorption near edge structure (XANES) spectroscopy.

Role of Hydrogen-Bond Interactions in CO Capture by Wet Phosphonium Formate Ionic Liquid: A Raman Spectroscopic Study.

The mechanism of CO absorption by a formate ionic liquid, [P ]HCOO, was studied by Raman spectroscopy. The band area for the symmetric CO stretching of the formate anion linearly decreases with the CO loading. From the slope of the decrease, 1 : 1 stoichiometry is proven between CO and the formate anion.

Excited-State Proton Transfer of Cyanonaphthols in Protic Ionic Liquids: Appearance of a New Fluorescent Species.

Excited-state proton transfer (ESPT) of 5-cyano-2-naphthol (5CN2) and 5,8-dicyano-2-naphthol (DCN2) in three different protic ionic liquids (PILs), triethylammonium trifluoromethanesulfonate ([NH][CFSO]), triethylammonium methanesulfonate ([NH][CHSO]), and triethylammonium trifluoroacetate ([NH][CFCOO]), was studied by time-resolved fluorescence. In [NH][CFSO], both 5CN2 and DCN2 showed fluorescence only from ROH* (normal form of substituted naphthol in the excited states), indicating that no ESPT occurred in [NH][CFSO]. For 5CN2 in [NH][CHSO], fluorescence bands from ROH* and RO* (anionic form of substituted naphthol in the excited states) were observed, indicating that 5CN2 could dissociate proton to surrounding solvents and form RO*.

Nuclear magnetic resonance study on rotational dynamics of water and benzene in a series of ionic liquids: anion and cation effects.

The rotational correlation times (τ(2R)) for polar water (D(2)O) molecule and apolar benzene (C(6)D(6)) molecule were determined in ionic liquids (ILs) by means of the (2)H (D) NMR spin-lattice relaxation time (T(1)) measurements. The solvent IL was systematically varied to elucidate the anion and cation effects separately. Five species, bis(trifluoromethylsulfonyl)imide (TFSI(-)), trifluoromethylsulfonate (TfO(-)), hexafluorophosphate (PF(6)(-)), chloride (Cl(-)), and formate (HCOO(-)), were examined for the anion effect against a fixed cation species of 1-butyl-3-methyl-imidazolium (bmim(+)).

Investigation of in situ oxalate formation from 2,3-pyrazinedicarboxylate under hydrothermal conditions using nuclear magnetic resonance spectroscopy.

We have investigated the assembly of a two-dimensional coordination polymer, Nd(2)(C(6)H(2)N(2)O(4))(2)(C(2)O(4))(H(2)O)(2), that has been prepared from the hydrothermal reaction of Nd(NO(3))(3)·6H(2)O and 2,3-pyrazinedicarboxylic acid (H(2)pzdc). In situ oxalate formation as observed in this system has been been investigated using (1)H and (13)C nuclear magnetic resonance spectroscopy, and a pathway for C(2)O(4)(2-) anion formation under hydrothermal conditions has been elucidated. The oxalate ligands found in Nd(2)(C(6)H(2)N(2)O(4))(2)(C(2)O(4))(H(2)O)(2) result from the oxidation of H(2)pzdc, which proceeds through intermediates, such as 2-pyrazinecarboxylic acid (2-pzca), 2-hydroxyacetamide, 3-amino-2-hydroxy-3-oxopropanoic acid, 2-hydroxymalonic acid, 2-oxoacetic acid (glyoxylic acid), and glycolic acid.

Rotational dynamics of benzene and water in an ionic liquid explored via molecular dynamics simulations and NMR T1 measurements.

The rotational dynamics of benzene and water in the ionic liquid (IL) 1-butyl-3-methylimidazolium chloride are studied using molecular dynamics (MD) simulation and NMR T(1) measurements. MD trajectories based on an effective potential are used to calculate the (2)H NMR relaxation time, T(1) via Fourier transform of the relevant rotational time correlation function, C(2R)(t). To compensate for the lack of polarization in the standard fixed-charge modeling of the IL, an effective ionic charge, which is smaller than the elementary charge is employed.

Frequency-domain investigation of the ionic mobility of triflate salts in tetrahydrofuran.

The frequency-dependent molar conductivities of two triflate salts, tetrabutylammonium triflate (TBATf) and lithium triflate (LiTf), in tetrahydrofuran are measured in the microwave frequency domain at the concentrations where the direct-current molar conductivity increases with concentration. The relaxation frequency of the conductivity of TBATf increases with concentration as was demonstrated by a simulation and theoretical calculation on a simple model system. However, the low-frequency side of the relaxation of the conductivity of LiTf grows with increasing concentration, suggesting the presence of large aggregates such as triple ions.

Hydrogen evolution from formic acid in an ionic liquid solvent: a mechanistic study by ab initio molecular dynamics.

The reversible decomposition of formic acid (HCOOH ⇌ CO(2) + H(2)) has been attracting attention for its potential utility in hydrogen storage and production. It is therefore of interest to explore the influence of solvents on the decomposition reaction. To this end, Born-Oppenheimer (BO) molecular dynamics (MD) calculations have been performed to explore the mechanism involved in hydrogen (H(2)) evolution from formic acid decomposition in an ionic liquid solvent.

Communication: exploring the reorientation of benzene in an ionic liquid via molecular dynamics: effect of temperature and solvent effective charge on the slow dynamics.

The rotational time correlation function (RTCF) of solute benzene molecules in the ionic liquid (1-butyl-3-methylimidazolium chloride) has been studied using classical molecular dynamics simulation. The effect of solvent charge on the functional form of RTCF was investigated by comparing four force fields for the solvent where the total charge on the anion and the cation was set to ±1e, ±0.7e, ±0.

Computational studies of room temperature ionic liquid-water mixtures.

Room temperature ionic liquids (IL) have been used in numerous applications in chemistry. Addition of water alters many of their properties making it possible to custom design solvents for specific applications. Along with experiments, computational studies using various approaches have provided key insights into the structure and dynamics of IL systems, as well as aggregate formation and phase behavior of the IL/water mixtures.

Controlling the equilibrium of formic acid with hydrogen and carbon dioxide using ionic liquid.

The equilibrium for the reversible decomposition of formic acid into carbon dioxide and hydrogen is studied in the ionic liquid (IL) 1,3-dipropyl-2-methylimidazolium formate. The equilibrium is strongly favored to the formic acid side because of the strong solvation of formic acid in the IL through the strong Coulombic solute-solvent interactions. The comparison of the equilibrium constants in the IL and water has shown that the pressures required to transform hydrogen and carbon dioxide into formic acid can be reduced by a factor of approximately 100 by using the IL instead of water.

Water as an in situ NMR indicator for impurity acids in ionic liquids.

A sensitive in situ NMR spectroscopic method for detecting acids contaminating ionic liquids (ILs) has been developed. The chemical shift and the spectral width of water added to ILs were used as indicators to measure the impurity acid level. Owing to the high resolution power of NMR, the detection limit is below the level of 10(-3) mol kg(-1).

Rotational dynamics of water and benzene controlled by anion field in ionic liquids: 1-butyl-3-methylimidazolium chloride and hexafluorophosphate.

The rotational correlation time (tau(2R)) is determined for D(2)O (polar) and C(6)D(6) (apolar) in 1-butyl-3-methylimidazolium chloride ([bmim][Cl]) and hexafluorophosphate ([bmim][PF(6)]) by measuring (2)H (D) nuclear magnetic resonance spin-lattice relaxation time (T(1)) in the temperature range from -20 to 110 degrees C. The tau(2R) ratio of water to benzene (tau(WB)) was used as a measure of solute-solvent attraction. tau(WB) is 0.

Slowdown of H/D exchange reaction rate and water dynamics in ionic liquids: deactivation of solitary water solvated by small anions in 1-butyl-3-methyl-imidazolium chloride.

The H/D exchange reaction and the rotational dynamics of heavy water (D2O) are studied at 50 degrees C in the ionic liquid, 1-butyl-3-methylimidazolium chloride ([bmim][Cl]), in the [D2O] range of 3-55 M. The initial H/D exchange rates are observed as 1.0 x 10(-7), 4.

Kinetic and equilibrium study on formic acid decomposition in relation to the water-gas-shift reaction.

Kinetics and equilibrium are studied on the hydrothermal decarbonylation and decarboxylation of formic acid, the intermediate of the water-gas-shift (WGS) reaction, in hot water at temperatures of 170-330 degrees C, to understand and control the hydrothermal WGS reaction. (1)H and (13)C NMR spectroscopy is applied to analyze as a function of time the quenched reaction mixtures in both the liquid and gas phases. Only the decarbonylation is catalyzed by HCl, and the reaction is first-order with respect to both [H(+)] and [HCOOH].