Choline Salts Research Articles

Isobaric Vapor–Liquid Equilibria for the Quaternary System Water + Ethanol + Ethylene Glycol + Choline Chloride and the Ternary System Water + Ethanol + Choline Chloride at 101.3 kPa

An organic salt choline chloride (ChCl) was introduced in ethylene glycol (EG) for improving the entrainer performance for ethanol dehydration by extractive distillation. The mixed solvent EG + ChCl with molar ratios of 8:1, 4:1, 2:1, and 4:3 were tested through vapor–liquid equilibrium (VLE) measurement for the quaternary system water + ethanol + EG + ChCl at 101.3 kPa. Data were also measured for the ternary system water + ethanol + ChCl. VLE behavior of the quaternary system was modeled successfully using the NRTL equation. The mean absolute deviations for the quaternary data were 0.24 K for equilibrium temperature and 0.0041 for vapor mole fraction of ethanol, while deviations for the ternary data were 0.15 K and 0.0032. As compared with EG alone, the existence of ChCl in the mixed solvent decreases the activity coefficient of water and increases the activity coefficient of ethanol, both leading to the enhancement of the relative volatility of ethanol to water. The azeotrope of water + ethanol can be removed with the addition of EG + ChCl 4:3 at a solvent mass fraction of 0.062, showing favorable entrainer performance for ethanol dehydration by extractive distillation.

High-energy hybrid electrochemical capacitor operating down to −40 °C with aqueous redox electrolyte based on choline salts

We report on a carbon/carbon hybrid electrochemical capacitor (hybrid EC) based on an aqueous redox-active electrolyte, which operates efficiently down to −40 °C. The electrolyte comprises choline iodide (ChI; 0.5 mol kg−1) as redox active component and choline nitrate (ChNO3; 5 mol kg−1) as supporting salt which enables the liquid state to be extended down to −42 °C, as proved by differential scanning calorimetry. Interestingly, the hybrid EC displays a high discharge capacitance of 81 F g−1 (at 0.1 A g−1; per total mass of electrodes), which is twice higher than its symmetric counterpart utilizing only an aqueous solution of ChNO3 (41 F g−1). The doubling of cell capacitance results from hybridization of the positive battery-type electrode (harnessing redox reactions of polyiodides trapped in carbon porosity) with the negative electrical double-layer (EDL) capacitive electrode. Even at −40 °C, the hybrid EC retains a high capacitance of 50 F g−1 and shows negligible ohmic drop. As its energy and power performance is in the same range as for EDL capacitors using tetraethylammonium tetrafluoroborate in acetonitrile, this new hybrid EC is a highly cost-effective and green alternative to these traditional systems.

Pyrene Fluorescence To Probe a Lithium Chloride-Added (Choline Chloride + Urea) Deep Eutectic Solvent.

Deep eutectic solvents (DESs) have shown promise as environmentally benign and inexpensive media with superior properties. Because of their structural features, they have potential to be versatile alternatives to the conventional electrolytes in various applications in science and technology. A mixture of a common and popular DES Reline, composed of salt choline chloride and H-bond donor urea in a 1:2 mole ratio, and lithium salt LiCl is investigated in a 298.15-358.15 K temperature range using a well-known multidimensional fluorescence probe pyrene. The band 1-to-band 3 emission intensity ratio (Py I1/ I3) at a given temperature reveals no change in the dipolarity of the pyrene cybotactic region of Reline on addition of up to 2.093 m(LiCl). Decrease in dipolarity of the medium on increasing temperature becomes less pronounced in the presence of LiCl. Excited-state intensity decay of pyrene fits best to a two-exponential decay equation irrespective of the temperature and LiCl concentration. While the shorter of the decay times does not vary with temperature, the longer one shows decrease with increasing temperature that is independent of the LiCl concentration. At a given temperature, addition of LiCl results in a slight decrease in the longer decay time because of the presence of Cl-, which facilitates nonradiative decay pathways of excited pyrene. Decrease in the pyrene decay time by an electron/charge acceptor quenching agent nitromethane is found to obey the Stern-Volmer equation, implying the quenching to be purely dynamic in nature. The estimated bimolecular quenching rate constant ( kq) first increases as LiCl is added to Reline before decreasing monotonically on further addition of LiCl. The decrease in kq with increasing LiCl is attributed to the exponential increase in the dynamic viscosity of Reline with LiCl addition. The initial increase is due to the stabilization of the partial positive charge that develops on excited pyrene during the electron/charge transfer to nitromethane by the added Cl- during the quenching process. The Stokes-Einstein equation is not obeyed within LiCl-added Reline, but it is found to be followed at a given LiCl concentration. Iso-viscous LiCl-added Reline mixtures are found to have significantly different kq values, suggesting the important role of LiCl in controlling the bimolecular quenching process within the system.

Deep eutectic solvents as simultaneous plasticizing and crosslinking agents for starch

The aim of this work was to prepare deep eutectic solvents (DES) made with choline salts with α-hydroxylate anions and glycerol and apply them as starch plasticizers. Additionally, crosslinking potential of polyfunctional anions from the salts was investigated. Starch/DES premixtures were rheologically and thermally (DSC, TGA) analyzed. Thermoplastic starch (TPS)/DES films were prepared via thermocompression molding. Influence of choline salt to glycerol molar ratio, type of anion and compression parameters on mechanical, dynamic mechanical, thermal and sorption properties as well as structural morphology (XRD, FTIR analysis) was studied. DES containing citrate anion exhibited parallel crosslinking and plasticizing ability of polysaccharide matrix as applied techniques confirmed. The higher choline citrate (CCit) content in DES the higher tensile strength, more amorphous structure and lower sorption degree to CCit:G 1:6 M ratio. XRD revealed that TPS/CCit-based DES films did not retrograde even after one year of storage. The best compression parameters for studied systems were: 140 °C, 12 tons, 10 min.

Rheological Behavior of Environmentally Friendly Viscoelastic Solutions Formed by a Rosin-Based Anionic Surfactant.

It is of great significance to explore novel applications of renewable resources. In this study, a rosin-based anionic surfactant (abbreviated R-11-2-Na), which contains a large hydrophobic group of 30 carbon atoms, was synthesized. R-11-2-Na forms wormlike micelles in the presence of the equimolar organic salt choline chloride, endowing solutions with strong viscoelasticity. The wormlike micellar solutions were investigated using rheology, small-angle X-ray scattering, and freeze-fracture transmission electron microscopy (FF-TEM) methods at 25 °C. Due to the strong van der Waals interactions caused by the large hydrophobic group contained in R-11-2-Na, the zero-shear viscosity (η0) of solutions showed extremely strong dependence on the concentration with an exponent of 23.4. The cross-sectional diameter of the wormlike micelles in the present system was significantly larger than that of the wormlike micelles formed by surfactants containing conventional alkyl tails. This finding may be attributed to the steric hindrance brought by the bulky and rigid dehydroabietic acid unit in the hydrophobic part. The wormlike micelles also showed high tolerance to the organic salt concentration. The present study reveals the notable qualities of rosin-based derivatives in forming complex fluids and facilitates new utilizations of forest resources.

Trimethylamine. Documentation of proposed values of occupational exposure limits (OELs)

Trimethylamine (TMA) is a gas at ambient temperature, which has a pungent, fishy odour. It is commercially available as a compressed gas, 40% aqueous solution or a 33 % solution in ethanol. It is used in organic synthesis, especially of choline salts, as a warning agent for natural gas and flotation agents, in the production of cationic starches, quaternary ammonium compounds, intense sweeteners and strongly basic anion exchange resins. Moreover, it is used in the production of disinfectants and insect attractants. TMA is irritating to the human respiratory tract, skin and eyes. The threshold of irritation was reported to be 1481 mg/m3 (median) after a single dose. No effects were observed in workers exposed to 0.24-19.5 mg/m³, most measurements being below 12.1 mg/m3. A LOAEC of 48 mg/m³ was established for human based on eyes, nose and throat irritation. Animal data with repeated inhalation exposure over 2 weeks revealed a LOAEC of 183.75 mg/m³ based on respiratory irritation in a rat study. Embryotoxic effects were observed in mice (NOAEL of 150 mg/kg bw/day). The Scientific Committee for Occupational Exposure Limits to Chemical Agents (SCOEL) has established OEL of 4.9 mg/m³ and STEL of 12.5 mg/m³. A MAC value has been derived using the RD50 value (147.62 mg/m3 for TMA) and multiplying it by a factor of 0.03. The Expert Group for Chemicals Agents has proposed to reduce the current MAC value from 12 mg/m³ to 4.9 mg/m³ and the current STEL value from 24 mg/m³ to 12.5 mg/m³, which is also in accordance with the values recommended by SCOEL. It has been proposed to remain the “I” (irritant) labelling of TMA. No bases for a BEI value have been found.

Effect of lithium chloride on the density and dynamic viscosity of choline chloride/urea deep eutectic solvent in the temperature range (303.15–358.15) K

Deep eutectic solvents (DESs) have emerged as superior alternatives to ionic liquids. Lithium salt-added DES mixtures may possess favorable properties as novel electrolyte media for Li-ion batteries. Densities and dynamic viscosities of LiCl-added DES reline (constituted of salt choline chloride and H-bond donor urea in 1:2 mol ratio) mixtures up to ∼0.2 molal LiCl [m(LiCl)] in the temperature range (303.15–358.15) K are presented. Decrease in density with increasing temperature is found to follow a simple linear expression. The density of LiCl-added reline also increases linearly with increasing m(LiCl) in the investigated temperature range. The temperature dependence of the dynamic viscosity of the (reline + LiCl) mixtures follows simple Arrhenius-type expression. The dynamic viscosity of LiCl-added reline mixture at a given temperature increases exponentially with increasing m(LiCl); the exponential increase being more prominent at lower temperatures. The trends in density and dynamic viscosity with temperature and m(LiCl) for LiCl-added DES reline are rather simplistic in comparison to Li salt-added ionic liquid mixtures.

Self-assembly of a short-chain ionic liquid within deep eutectic solvents.

Ionic liquids (ILs) and deep eutectic solvents (DESs) are receiving increased attention from both academic and industrial research due to their immense application potential. These designer solvents are environmentally friendly in nature with tunable physicochemical properties. In the present investigation, we have studied the aggregation behavior of a short-chain IL 1-butyl-3-methylimidazolium octylsulphate [Bmim][OS] within aqueous DESs using fluorescence, UV-vis, dynamic light scattering (DLS) and FT-IR spectroscopic techniques. We have prepared two DESs, ChCl–urea and ChCl–Gly, which are obtained by heating a mixture of an ammonium salt choline chloride with hydrogen bond donor urea or glycerol, respectively, in 1 : 2 molar ratios. The local microenvironment and size of the aggregates are obtained from steady state fluorescence (using pyrene and pyrene-1-carboxaldehyde as polarity probes) and DLS measurements, respectively. DLS results shows that IL [Bmim][OS] forms relatively larger micelles within the aqueous solution of DES ChCl–urea (avg. hydrodynamic radii = 209 nm) than compared to ChCl–Gly (avg. hydrodynamic radii = 135 nm). A significant decrease in the critical micelle concentration and increase in the aggregation number (Nagg) are observed within DES solutions as compared to that in water, thus indicating that the micellization process of the IL [Bmim][OS] is much favored in the DES solutions. Molecular interactions of [Bmim][OS] in DESs are revealed from FT-IR spectroscopic investigation. Furthermore, these systems were applied to study the IL-drug binding of the antidepressant drug promazine hydrochloride (PH).

Superbase‐Added Choline Chloride‐Based Deep Eutectic Solvents for CO2 Capture and Sequestration

AbstractDeep eutectic solvents (DESs) have emerged as inexpensive and environmentally‐benign liquid media for potential usage in chemical sciences. CO2 capture and sequestration by various substances is an active area of research in green chemistry. CO2 capture ability of DES‐based systems composed of salt choline chloride mixed with hydrogen bond donors urea (named reline), ethylene glycol (named ethaline), and monoethanolamine (named MEACC), are assessed in the absence and presence of three superbases: 1,5‐diazabicyclo[4.3.0]‐non‐5‐ene (DBN), 1,8‐diazabicyclo[5.4.0]undec‐7‐ene (DBU), and 1,5,7‐triazabicyclo[4.4.0]‐dec‐5‐ene (TBD), respectively. Addition of superbase is found to significantly increase the CO2 capture ability of the DESs reline and ethaline; for the DES MEACC, the CO2 capture ability is not changed much as monoethanolamine and MEACC on their own exhibit appreciable CO2 capture efficiency. It is found that the overall efficiency of CO2 capture is the best with superbase DBN as compared to DBU or TBD due to the lower steric hindrance around the imine structure. Presence of glycerol in the superbase‐added DESs results in decrease in CO2 capture ability due to significantly lower solubility of CO2 in glycerol. 13C NMR, FTIR and Raman spectroscopic measurements reveal that major part of the captured CO2 binds covalently to the electron‐rich functionalities present on the components of the DES with superbase assisting this association. The reversibility of the captured CO2 is assessed by introducing N2 gas into the CO2 captured superbase‐added DES system; it is found that only 21–25% CO2 by weight could be removed from the system through five cycles. Heating the CO2 captured superbase‐added DES system to 60 °C and 100 °C results in loss of only 23% and 35% CO2 by weight, respectively. Intramolecular excimer intensity of 1,10‐bis(1‐pyrenyl)decane and steady‐state fluorescence anisotropy of rhodamine 6G fluorescence probes effectively monitor the CO2 capture process as viscosity of the superbase‐added DES increases as more‐and‐more CO2 is captured. Efficiency, effectiveness, and robustness of superbase‐added DES‐based systems towards CO2 capture and sequestration is amply highlighted.

Choline chloride vs choline ionic liquids for starch thermoplasticization

Native starch containing 12% water was melt processed in presence of 23% of various plasticizers at 120°C, either by simple compression molding or by extrusion using a laboratory scale microcompounder. Glycerol, a typical starch plasticizer, was used as a reference and compared to three choline salts: raw choline chloride (which is a solid in dry state with a melting point above 300°C), and two ionic liquids synthesized from this precursor (choline acetate and choline lactate, liquids below 100°C). These ionic plasticizers were shown to allow a more efficient melting of native starch in both processes. The investigation of macromolecular structure changes during processing shows that this efficiency can be ascribed to a starch chain scission mechanism, resulting in lower specific mechanical energy input need for starch thermoplasticization compared to glycerol plasticized starch. Compared to the synthesized ionic liquids, raw commercial choline chloride leads to a good compromise between limited chain scission, and final water uptake and thermomechanical properties.

Aggregation of Carbocyanine Dyes in Choline Chloride-Based Deep Eutectic Solvents in the Presence of an Aqueous Base.

Deep eutectic solvents (DESs) have shown potential as novel media to support molecular aggregation. The self-aggregation behavior of two common and popular carbocyanine dyes, 5,5',6,6'-tetrachloro-1,1'-diethyl-3,3'-di(4-sulfobutyl)-benzimidazole carbocyanine (TDBC) and 5,5'-dichloro-3,3'-di(3-sulfopropyl)-9-methyl-benzothiacarbo cyanine (DMTC), is investigated within DES-based systems under ambient conditions. Although TDBC is known to form J-aggregates in basic aqueous solution, DMTC forms H-aggregates under similar conditions. The DESs used, glyceline and reline, are composed of salt choline chloride and two vastly different H-bond donors, glycerol and urea, respectively, in 1:2 mol ratios. Both DESs in the presence of base are found to support J-aggregates of TDBC. These fluorescent J-aggregates are characterized by small Stokes' shifts and subnanosecond fluorescence lifetimes. Under similar conditions, DMTC forms fluorescent H-aggregates along with J-aggregates within the two DES-based systems. The addition of cationic surfactant cetyltrimethylammonium bromide (CTAB) below its critical micelle concentration (cmc) to a TDBC solution of aqueous base-added glyceline shows the prominent presence of J-aggregates, and increasing the CTAB concentration to above cmc results in the disruption of J-aggregates and the formation of unprecedented H-aggregates. DMTC exclusively forms H-aggregates within a CTAB solution of aqueous base-added glyceline irrespective of the surfactant concentration. Anionic surfactant, sodium dodecylsulfate (SDS), present below its cmc within aqueous base-added DESs supports J-aggregation by TDBC; for similar SDS addition, DMTC forms H-aggregates within the glyceline-based system whereas both H- and J-aggregates exist within the reline-based system. A comparison of the carbocyanine dye behavior in various aqueous base-added DES systems to that in aqueous basic media reveals contrasting aggregation tendencies and/or efficiencies. Surfactants as additives are demonstrated to control and modulate carbocyanine dye self-aggregation within DES-based media. The unique nature of DESs as alternate media toward affecting cyanine dye aggregation is highlighted.

Hydrogen Bond Donor/Acceptor Cosolvent-Modified Choline Chloride-Based Deep Eutectic Solvents.

Deep eutectic solvents (DESs) have emerged as nontoxic and inexpensive alternatives not only to the common organic solvents but to the ionic liquids as well. Some of the common and popular, and perhaps the most investigated, DESs are the ones comprising an ammonium salt and an appropriate hydrogen bond (HB) donor in a predetermined mole ratio. The formation of the DES is attributed to the H-bonding interaction(s) present between the salt and the HB donor. Consequently, addition of a predominantly HB donor or a predominantly HB acceptor cosolvent to such DESs may result in intriguing features and properties. We present investigation of two DESs constituted of salt choline chloride along with HB donors urea and glycerol, respectively, in 1:2 mol ratio, named reline and glyceline as the cosolvent of very high HB donating acidity and no HB accepting basicity 2,2,2-trifluoroethanol (TFE) and of very high HB accepting basicity and no HB donating acidity hexamethylphosphoramide (HMPA), respectively, is added. TFE shows up to 0.25 mole fraction miscibility with both reline and glyceline. While up to 0.25 mole fraction HMPA in glyceline results in transparent mixtures, this cosolvent is found to be completely immiscible with reline. From the perspective of the solvatochromic absorbance and fluorescence probes, it is established that the cybotactic region dipolarity within up to 0.25 mole fraction TFE/HMPA-added DES strongly depends on the functionalities present on the solute. Fourier transform infrared absorbance and Raman spectroscopic investigations reveal no major shifts in vibrational transitions as TFE/HMPA is added to the DES; spectral band broadening, albeit small, is observed nonetheless. Excess molar volumes and excess logarithmic viscosities of the mixtures indicate that while TFE may interstitially accommodate itself within H-bonded network of reline, it does appear to form H-bonds with the constituents of the glyceline. Increase in overall net repulsive interactions as HMPA is added to glyceline is suggested by both positive excess molar volumes and excess logarithmic viscosities. The addition of HB donor/acceptor cosolvent appears to disturb the salt-HB donor equilibria within DES via complex interplay of interactions within the system.

Efficacy of herbicidal ionic liquids and choline salt based on 2,4-D

Five quaternary ammonium salts with the 2,4-dichlorophenoxyacetate [2,4-D] anion were synthesized and their physicochemical properties and efficacy against weeds was investigated. The following cations were used in the synthesis: (2-hydroxyethyl)trimethylammonium [Choline], (2-chloroethyl)trimethylammonium [CC], cocotrimethylammonium [Arq], bis(2-hydroxyethyl)cocomethylammonium [Etq C] and bis(2-hydroxyethyl)methyloleylammonium [Etq O]. Among them, four compounds: [CC][2,4-D], [Arq][2,4-D], [Etq C][2,4-D] and [Etq O][2,4-D] were classified as herbicidal ionic liquids (HILs).Data from greenhouse studies showed similar or better efficacy of ionic liquids based on 2,4-D compared to commercial formulations of 2-ethylhexyl ester and dimethylammonium salt and also to choline salts which is recently marketed but in the mixture with glyphosate (Enlist Duo, Dow AgroSciences LLC). HILS with 2,4-D anion also showed excellent efficacy in field experiments. In this case, all tested HILs demonstrated several times higher efficacy compared to choline, dimethylammonium salts and 2-ethylhexyl ester.All the described results suggest that selection of an appropriate cation allows to control the physicochemical properties of studied herbicidal ionic liquids, which proved to have a significant impact on its biological activity.

Fluorescence quenching of polycyclic aromatic hydrocarbons within deep eutectic solvents and their aqueous mixtures

Two common and popular deep eutectic solvents (DESs) composed of the salt choline chloride and H-bond donors glycerol and urea in 1:2mol ratio named glyceline and reline, respectively, are investigated for the analysis of polycyclic aromatic hydrocarbons (PAHs) using quenching of both steady-state and time-resolved fluorescence of ten different PAHs by nitromethane at 30°C. Based on their quenching efficiencies, the PAHs are divided into two groups – group 1 is constituted of the five PAHs whose fluorescence are quenched less effectively by nitromethane whereas the other five exhibiting high quenching efficiency are associated to group 2. Quenching of steady-state fluorescence of group 1 PAHs by nitromethane, albeit not very significant, follow a simple Stern-Volmer behavior. The excited-state emission intensity decay of these PAHs, in both absence and presence of nitromethane, fit best to a single exponential model with small but monotonic decrease in lifetimes. The decrease in lifetime also follows Stern-Volmer behavior, however, the quenching constants (KD) are lower than those obtained from steady-state fluorescence (KSV). This is ascribed to the possible formation of charge-transfer complex between the PAH and the nitromethane. Steady-state fluorescence quenching of group 2 PAHs exhibit distinct upward curvature from linear Stern-Volmer behavior implying highly efficient quenching. The intensity decay fits best to a double exponential decay model with longer of the decay times following simple Stern-Volmer behavior. Formation of a complex or the presence of nitromethane within the quenching sphere of action of the PAH having short decay time is proposed. Quenching behavior was found to be similar irrespective of the identity of the DES. A representative group 2 PAH, pyrene, is employed to investigate diffusion dynamics within aqueous mixtures of the two DESs. The bimolecular quenching rate constant (kq) is found to increase linearly with the mole fraction of water (xw) in aqueous mixtures of both the DESs. Stokes-Einstein relationship is not obeyed within the DES aqueous mixtures and is attributed to be due to the inherent heterogeneity of the mixtures. Diffusion dynamics of pyrene-nitromethane pair is compared with that of a tracer fluorescein isothiocyanate obtained using fluorescence correlation spectroscopy. Good correlation between the two highlights generality of diffusion dynamics with aqueous DES mixtures as far as solutes are concerned.

Enhanced removal of lead from contaminated soil by polyol-based deep eutectic solvents and saponin

Deep eutectic solvents (DESs) are a class of green solvents analogous to ionic liquids, but less costly and easier to prepare. The objective of this study is to remove lead (Pb) from a contaminated soil by using polyol based DESs mixed with a natural surfactant saponin for the first time. The DESs used in this study were prepared by mixing a quaternary ammonium salt choline chloride with polyols e.g. glycerol and ethylene glycol. A natural surfactant saponin obtained from soapnut fruit pericarp, was mixed with DESs to boost their efficiency. The DESs on their own did not perform satisfactory due to higher pH; however, they improved the performance of soapnut by up to 100%. Pb removal from contaminated soil using mixture of 40% DES-Gly and 1% saponin and mixture of 10% DES-Gly and 2% saponin were above 72% XRD and SEM studies did not detect any major corrosion in the soil texture. The environmental friendliness of both DESs and saponin and their affordable costs merit thorough investigation of their potential as soil washing agents.

Organic-phase biological buffers for biochemical and biological research in organic media

A long-standing problem in enzymatic catalysis in organic media is finding a buffer that keeps a constant pH, as there are no commercially available biological buffers for such media. The biological buffers such as Good's buffers that are commonly used in aqueous media are insoluble in almost all organic solvents, and there is nowadays a pressing need for a buffer for organic media. Good's buffers were designed based on sets of criteria which make them extensively used in biochemical and biological research. In this context, we show that when Good's buffers turned into ionic liquids, so-called Good's buffer ionic liquids (GB-ILs), they became highly soluble in polar organic media, such as methanol and ethanol. This implies that a huge number of organo-soluble buffers are expected to be commercially available for such solvents. Twenty five GB-ILs (tetramethylammonium, tetraethylammonium, tetrabutylammonium, 1-ethyl-3-methy limidazolium, and choline salts of Tricine, TES, MES, HEPES, and CHES) were tested as organic-phase buffers for pure methanol, and their buffer capacities in methanol were found to be very close to that in water. A series of mixed GB-ILs was also formulated as universal buffers in methanol. Conductor-like screening model for real solvents (COSMO-RS) calculations were performed to show why GB-ILs gained high solubility in methanol.

Efficient separation of phenolic compounds from model oil by the formation of choline derivative-based deep eutectic solvents

Abstract Phenolic compounds are an important class of compounds for organic chemical industry. In their traditional production processes, strong acid and base have to be used for the separation of phenolic compounds from oils, which often causes serious environmental problems. In this work, choline derivative salts [N 1,1, n C 2 OH]Cl ( n = 1, 4, 6, 8) have been used as new extractants for the separation of 26 kinds of phenolic compounds from model oil (toluene) by forming deep eutectic solvents (DESs). It is found that only 16 kinds of phenolic compounds can be removed from toluene with single-step removal efficiency from 28.1% to 94.7%, strongly depending on the chemical structure of phenolic compounds. The nature, position and number of substituent groups in the phenolic compounds have a great effect on their removal efficiency. Far infrared spectroscopy and density functional theory calculations indicate that hydrogen bonds formed between –OH of the phenolic compounds and anion of the choline derivative salts is the main driving force for such DES-based separation. The correlation observed experimentally between structure of phenolic compounds and their removal efficiencies has been discussed from hydrogen bonding in DESs, electrostatic interaction of cation and anion of the choline salts, and solvation of the phenolic compounds and choline salts in the oil.

Correction to Interesting Morphological Behavior of Organic Salt Choline Fenofibrate: Effect of Supersaturation and Polymeric Impurity

Correction to Interesting Morphological Behavior of Organic Salt Choline Fenofibrate: Effect of Supersaturation and Polymeric Impurity

Conversion of glucose into 5-hydroxymethylfurfural with boric acid in molten mixtures of choline salts and carboxylic acids

The conversion of glucose into a potential platform chemical for fuels and plastics, 5-hydroxymethylfurfural (HMF), has been studied using B(OH)3 as a promoter in different solvents, namely molten mixtures made of choline salts and carboxylic acids, with the aim of developing an inexpensive and less harmful alternative to Cr/ionic liquid systems. Choline chloride-based molten mixtures afforded poor yields of HMF, whereas the yields were improved by replacing choline chloride with choline dihydrogen citrate. The combination of choline dihydrogen citrate and glycolic acid was the best choice, providing an HMF yield of ∼60% at 140 °C within 4 h by adding a small volume of water as a co-solvent.

Free-radical polymerization of itaconic acid in the presence of choline salts: Mechanism of persulfate decomposition

Kinetics of decomposition of persulfate activated by choline in aqueous solution has been studied. Additionally, the products of choline degradation were analyzed by 1H NMR spectroscopy, and betaine aldehyde was identified as the main oxidation product. Thus, radical-chain redox mechanism is postulated to explain experimental results. The mechanism was successfully verified using kinetic modeling approach. Moreover, it was found that due to formation of complex of itaconic acid and choline chloride, the salt solubility of the acid in water was increased. Finally, free-radical polymerization of itaconic acid initiated by persulfate in aqueous solution of the choline salt yielded poly(itaconic acid) with higher molecular weight and increased polydispersity.