- Structure-energy relations in hen egg white lysozyme observed during refolding from a quenched unfolded state
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We use infrared spectroscopy to study the evolution of protein folding intermediate structures on arbitrarily slow time scales by rapidly quenching thermally unfolded hen egg white lysozyme in a glassy matrix, followed by reheating of the protein to refold; upon comparison with differential scanning calorimetric experiments, low-temperature structural changes that precede the formation of energetic native contacts are revealed. The Royal Society of Chemistry 2009.
- Cho, Theresa Y.,Byrne, Nolene,Moore, David J.,Pethica, Brian A.,Austen Angell,Debenedetti, Pablo G.
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- Enhanced solubilization of membrane proteins by alkylamines and polyamines
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Around 25% of proteins in living organisms are membrane proteins that perform many critical functions such as synthesis of biomolecules and signal transduction. Membrane proteins are extracted from the lipid bilayer and solubilized with a detergent for biochemical characterization; however, their solubilization is an empirical technique and sometimes insufficient quantities of proteins are solubilized in aqueous buffer to allow characterization. We found that addition of alkylamines and polyamines to solubilization buffer containing a detergent enhanced solubilization of membrane proteins from microsomes. The solubilization of polygalacturonic acid synthase localized at the plant Golgi membrane was enhanced by up to 9.9-fold upon addition of spermidine to the solubilization buffer. These additives also enhanced the solubilization of other plant membrane proteins localized in other organelles such as the endoplasmic reticulum and plasma membrane as well as that of an animal Golgi-localized membrane protein. Thus, addition of alkylamines and polyamines to solubilization buffer is a generally applicable method for effective solubilization of membrane proteins. The mechanism of the enhancement of solubilization is discussed. Published by Wiley-Blackwell.
- Yasui, Kazutoshi,Uegaki, Masamichi,Shiraki, Kentaro,Ishimizu, Takeshi
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- Volumetric properties of ethylammonium nitrate + γ-butyrolactone binary systems: Solvation phenomena from density and raman spectroscopy
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The densities of binary mixtures of ethylammonium nitrate (EAN) ionic liquid (IL) and γ-butyrolactone (BL) have been measured over the entire range of concentrations at 293.15, 298.15, 303.15, 308.15, 313.15 and 318.15 K and under ambient pressure. Experimental densities were used to calculate excess molar volumes VmE, isobaric and excess isobaric expansion coefficients α and α E. The excess molar volumes have both negative and positive values, while the excess isobaric expansion coefficients are negative over the entire composition range. The V mE values have been fitted to the Redlich-Kister polynomial equation, and other volumetric properties such as the partial molar volumes V mi, the excess partial molar volume Vmi E and the partial molar volumes at infinite dilution V miE were calculated. The results have been interpreted in terms of dipole-dipole interactions, hydrogen bonds formation and structural factors of these mixtures. The FT-Raman spectroscopy study of the intensity variations of some characteristic bands such as the C=O stretching band at 1763 cm-1, C-O symmetric stretching band at 932 cm-1 and C-C stretching band at 872 cm-1 of BL has been undertaken. The solvation phenomenon is evidenced by the modifications of these band intensities due to the presence of the IL ions. Moreover, the Raman spectroscopy corroborates the volumetric study. The average number of BL molecules in the primary solvation shell of the ethylammonium cation lies between 3 and 4 depending on the temperature.
- Zarrougui, Ramzi,Dhahbi, Mahmoud,Lemordant, Daniel
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- Aggregation behavior of long-chain piperidinium ionic liquids in ethylammonium nitrate
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Micelles formed by the long-chain piperidinium ionic liquids (ILs) N-alkyl-N-methylpiperidinium bromide of general formula CnPDB (n = 12, 14, 16) in ethylammonium nitrate (EAN) were investigated through surface tension and dissipative particle dynamics (DPD) simulations. Through surface tension measurements, the critical micelle concentration (cmc), the effectiveness of surface tension reduction (Πcmc), the maximum excess surface concentration (Λmax) and the minimum area occupied per surfactant molecule (Amin) can be obtained. A series of thermodynamic parameters (ΔG0m, ΔH0m and ΔS0m) of micellization can be calculated and the results showed that the micellization was entropy-driven. In addition, the DPD simulation was performed to simulate the whole aggregation process behavior to better reveal the micelle formation process.
- Dai, Caili,Du, Mingyong,Liu, Yifei,Wang, Shilu,Zhao, Jianhui,Chen, Ang,Peng, Dongxu,Zhao, Mingwei
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- Measurements and correlation of viscosity and conductivity for the mixtures of ethylammonium nitrate with organic solvents
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Transport physicochemical properties of binary mixtures ionic liquid/organic solvent (IL/OS) were studied. Systematical measurements of viscosities (η) and conductivities (Λ) for the binary mixtures of ethylammonium nitrate (EAN) with different OS, over the whole composition range and at temperature ranging from 273.15 K to 313.15 K, were performed. The variation tendency of viscosities/conductivities with composition of the mixtures was explained through the disruption of molecular solutes to ionic association or aggregation of the ionic liquids and correlation between them is carried out by means of Walden product (W). A semi-empirical equation proposed by Jones and Dole was used to describe the variation of viscosity with salt concentration (C). At low concentration of EAN, molar conductivity follows cube root law predicted by the quasi-lattice model. The two transport processes are well described by Arrhenius type laws from which the activation energies for the viscosity (Ea,η) and conductivity (Ea,Λ) are deduced.
- Litaeim, Yousra,Dhahbi, Mahmoud
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- Reversible Photoresponsive Molecular Alignment of Liquid Crystals at Fluid Interfaces with Persistent Stability
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This work demonstrates a noninvasive approach to control alignment of liquid crystals persistently and reversibly at fluid interfaces by using a photoresponsive azobenzene-based surfactant dissolved in an ionic liquid (IL), ethylammonium nitrate (EAN). As the first report on the orientational behavior of LCs at the IL/LC interface, our study also expands current understanding of alignment control of LCs at the aqueous/LC interface by adding electrolytes into aqueous solutions. The threshold concentration for switching the optical responses of LCs can be changed just by simply manipulating the ratio of EAN to H2O. This work will inspire fundamental studies and novel applications of using the LC-based imaging technique to investigate various chemical and biological events in ILs.
- Tian, Tongtong,Hu, Qiongzheng,Wang, Yi,Gao, Yanan,Yu, Li
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- Anhydrous proton exchange membranes at elevated temperatures: Effect of protic ionic liquids and crosslinker on proton conductivity
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A series of novel anhydrous proton exchange membranes (poly(vinyl alcohol)-citric acid-ionic liquid (PVA-CA-IL)) were prepared using the low cost ionic liquids ethylammonium nitrate (EAN), diethylammonium nitrate (DEAN), and triethylammonium nitrate (TEAN) as conductive fillers in PVA support membrane. The properties of the PVA-CA-IL membranes can be controlled by changing the molar ratio of the PVA, ILs and CA. The thermal stability of PVA-CA-IL membrane was measured by thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC), and the microstructure was investigated using scanning electron microscopy (SEM) and the Anton-paar SAX Sess mc2 system (SAXS). The effects of temperature, ILs and crosslinker dosage on proton conductivity were also systematically investigated. The results showed that the PVA-CA-IL membranes had excellent performance. The proton conductivity of PVA-CA-EAN (mole ratio = 1:0.05:0.4) could reach up to 7.8 mS cm-1 at 140 °C. The introduction of ionic liquid into PVA membrane constituted a new and efficient kind of anhydrous proton exchange membrane. This journal is
- Yang, Yi,Gao, Hejun,Zheng, Liqiang
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- Liquid crystalline phases of the amphiphilic ionic liquid n -hexadecyl- n -methylpyrrolidinium bromide formed in the ionic liquid ethylammonium nitrate and in water
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The phase behavior of a surfactant-like ionic liquid, N-hexadecyl-N- methylpyrrolidinium bromide (C16MPB), was studied in both water and a room temperature ionic liquid, ethylammonium nitrate (EAN). Polarized optical microscopy (POM) and small-angle X-ray scattering (SAXS) measurements were employed to investigate the phase behavior of the two systems and to determine which lyotropic liquid crystalline (LC) phases were formed. With increasing C16MPB concentration, an isotropic solution phase, a hexagonal (H1) phase, and a cubic phase (V2) are all present in either EAN or H2O. The structural parameters of the H1 phase were calculated from SAXS patterns, which show the structural changes as a function of the amount of C16MPB. The rheological results reveal that the H1 phase constructed by C16MPB in EAN displays a typical Maxwell behavior, whereas the H1 phase formed by C 16MPB in water shows a gel-like behavior, unlike traditional cationic surfactants. POM and differential scanning calorimetry (DSC) results demonstrate that the lyotropic LC phase in EAN has a higher thermal stability than that formed in H2O, which may be important to extend the applications of the LC phase.
- Zhao, Mingwei,Gao, Yanan,Zheng, Liqiang
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- First fluorinated zwitterionic micelle with unusually slow exchange in an ionic liquid
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The micellization of a fluorinated zwitterionic surfactant in ethylammonium nitrate (EAN) was investigated. The freeze-fracture transmission electron microscope (FF-TEM) observations confirm the formation of spherical micelles with the average diameter 25.45 ± 3.74 nm. The micellization is an entropy-driven process at low temperature but an enthalpy-driven process at high temperature. Two sets of 19F NMR signals above the critical micelle concentration (cmc) indicate that the unusually slow exchange between micelles and monomers exists in ionic liquid; meanwhile, surfactant molecules are more inclined to stay in micelle states instead of monomer states at higher concentration. Through the analysis of the half line width (Δν 1/2), we can obtain the kinetic information of fluorinated zwitterionic micellization in an ionic liquid.
- Wang, Xiaolin,Long, Panfeng,Dong, Shuli,Hao, Jingcheng
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- Enhanced photo-electrochemical water oxidation on MnOx in buffered organic/inorganic electrolytes
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Manganese oxide (MnOx) materials have been widely studied as electro-catalysts for the water oxidation reaction. Although the electronic structure of MnO2 (band gap ～2 eV) indicates it could be a promising photo-anode material for solar water splitting, so far only quite small photocurrents have been obtained from manganese oxides. Here, we show that the photo-electrochemical water oxidation performance of MnOx films can be significantly improved by using buffered aqueous electrolytes containing amine ionic liquids. The buffered conditions to maintain a constant proton activity and the amine salt are both crucial for achieving high photocurrents. Photocurrents as high as 4.5 mA cm-2 were obtained at 1.0 V vs. SCE (η = 540 mV) in Bi buffered n-butylammonium nitrate (BAN) electrolyte at pH 9. The incident photon-to-current efficiency (IPCE) was found to be greater than 3% at 400 nm and 4% at 370 nm. Both H2O2 and O2 are produced simultaneously in this system, with the potential subsequent decomposition of the H2O2 to form oxygen. An acceleration of the decomposition of H2O2 under illumination is proposed to explain the photocurrent improvement.
- Zhou, Fengling,McDonnell-Worth, Ciaran,Li, Haitao,Li, Jiaye,Spiccia, Leone,MacFarlane, Douglas R.
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- Cytotoxicity of protic ionic liquids towards the HaCat cell line derived from human skin
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In this work we have investigated the toxicity of 10 PILs, consisting of ethyl-, ethanol-, diethanol- and triethanolammonium cations paired with nitrate, formate, acetate and glycolate anions. Their toxicity was quantified by the EC50 values of each of these PILs towards HaCat cells, which are derived from human skin cells. Additional salts and solvents were used for comparison including DMSO, choline chloride, potassium nitrate, sodium acetate and ethanol to distinguish if the toxicity changes were due to ionicity, short chain amphiphilic behaviour, or specific ion effects. The toxicity followed the general trend of choline chloride acetate containing PILs DMSO sodium acetate ethanol nitrate containing PILs or salt. Ethanolammonium acetate and ethylammonium acetate were identified as having the lowest toxicities of the PILs, being slightly more toxic than choline chloride or DMSO. Overall the toxicity was found to be highly dependent on the cation and anion combination, with the anion having a stronger affect. It was evident that the PILs can be tailored to vary their toxicities, and this is expected to be dependent on which cell lines are used.
- Abraham, Amanda N.,Arunkumar, Radhika,Drummond, Calum J.,Greaves, Tamar L.,Shukla, Ravi
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- Understanding the Role of Protic Ionic Liquids (PILs) in Reactive Systems: Rational Selection of PILs for the Design of Green Synthesis Strategies for Allylic Amines and β-Amino Esters
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The reactive behaviour of protic ionic liquids (PILs) has been shown to be governed not only by their chemical structures but also by their global compositions, which include the presence of free acids and bases at equilibrium with ionic pairs. Six PILs composed of primary, secondary, or tertiary alkyl ammonium cations with two couterions, nitrate or acetate, were tested in model reactions with unsaturated substrates. The free species that were naturally present in these liquids were identified by cyclic voltammetry. Only tributylammonium nitrate was found to be mostly composed just of the ionic pair; the other five PILs also contain variable amounts of free acid and amine. In reactive systems, these free species determine the products of the reaction. In particular, allylic amines and β-amino esters were obtained in good yields (91 and 75 %, respectively) by reaction of conjugated dienes and acrylates in the presence of PILs. By taking into account the actual composition of each PIL, it was possible to direct the reaction path towards a specific product with good yields, to ensure acid catalysis, to avoid polymerization of the substrate, and to promote phase transfer of products. These results establish some useful guidelines for the rational design of new PIL-based one-step synthetic strategies.
- Bravo, María V.,Fernández, José L.,Adam, Claudia G.,Della Rosa, Claudia D.
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p. 919 - 926
(2019/07/31)
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- Protic ionic liquids as catalysts for a three-component coupling/hydroarylation/dehydrogenation tandem reaction
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Protic ionic liquids with nitrate anions were used as solvents and catalysts for a three-component oxidative dehydrogenation tandem reaction via the coupling and hydroarylation of benzaldehyde, aniline, and phenylacetylene to a quinoline derivative. The reaction was supported by air and microwave irradiation. The presence of nitrate as counter anion in the protic ionic liquids was essential for the reaction.
- Muntzeck, Maren,Wilhelm, René
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p. 515 - 519
(2018/06/18)
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- Protic ionic liquids (PILs) nanostructure and physicochemical properties: Development of high-throughput methodology for PIL creation and property screens
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A high-throughput approach was developed in order to prepare and dry a series of protic ionic liquids (PILs) from 48 Bronsted acid-base combinations. Many combinations comprised an alkyl carboxylic acid paired with an alkyl amine. Visual screens were developed to identify which acid-base combinations formed PILs, and of those, which PILs were likely to have high surface tensions, low viscosities, and low melting points. The surface tension screen was validated through pendant drop surface tension measurements. Karl Fischer coulometric titration was used to obtain the water contents, and it was noted that there is a considerable difference in the drying rate throughout this series of PILs. It was observed that an octyl chain present on either the cation or anion was detrimental to the formation of a PIL with a low melting point, and instead increased the likelihood of a gel or solid forming. The nanostructure of the PILs was determined, using synchrotron small and wide angle X-ray scattering (SAXS/WAXS), to consist of polar and non-polar domains, with the alkyl chains on the cation and anion intercalating. The results indicate that both the alkyl chain on the cation and/or anion contribute to the correlation distance, for the intermediate range order, with the expectation that there is charge alternation of the ions in the polar region. The maximum correlation distance was observed when there was an alkyl chain present on only one ion. This correlation distance could be significantly reduced by varying the alkyl chain length present on the other ion, which was attributed to increased disorder and interdigitation of chains, and to toe-to-toe alignment of the chains. To the best of our knowledge this is the first PIL report into the effect of having an alkyl chain present on both the cation and the anion. This journal is
- Greaves, Tamar L.,Ha, Krystal,Muir, Benjamin W.,Howard, Shaun C.,Weerawardena, Asoka,Kirby, Nigel,Drummond, Calum J.
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p. 2357 - 2365
(2015/02/19)
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- A Metal-Free and Ionic Liquid-Catalyzed Aerobic Oxidative Bromination in Water
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A metal-free aerobic oxidative bromination of aromatic compounds in water has been developed. Hydrobromic acid is used as a bromine source and 2-methylpyridinium nitrate ionic liquid is used as a recyclable catalyst. Water is used as the reaction mediate. This is the first report of aerobic oxidative bromination using only catalytic amount of metal-free catalyst. This system shows not only high bromine atom economy, but also high bromination selectivity. The possible mechanism and the role of the catalyst in this system have also been discussed.
- Wang, Jian,Chen, Shu-Bin,Wang, Shu-Guang,Li, Jing-Hua
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p. 513 - 517
(2015/03/30)
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- Nonaqueous lyotropic liquid-crystalline phases formed by gemini surfactants in a protic ionic liquid
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The aggregation behaviors of three Gemini surfactants [(CsH 2s-α,ω-(Me2N+CmH 2m+1Br-)2, s = 2, m = 10, 12, 14] in a protic ionic liquid, ethylammonium nitrate (EAN), have been investigated. The polarized optical microscopy and small-angle X-ray scattering (SAXS) measurements are used to explore the lyotropic liquid crystal (LLC) formation. Compared to the LLCs formed in aqueous environment, the normal hexagonal and lamellar phases disappear. However, with increasing the surfactant concentration, a new reverse hexagonal phase (HII) can be mapped over a large temperature range except for other ordered aggregates including the isotropic solution phase and a two-phase coexistence region. The structural parameters of the HII are calculated from the corresponding SAXS patterns, showing the influence of surfactant amount, alkyl chain length, and temperature. Meanwhile, the rheological profiles indicate a typical Maxwell behavior of the LLC phases formed in EAN.
- Wang, Xudong,Chen, Xiao,Zhao, Yurong,Yue, Xiu,Li, Qiuhong,Li, Zhihong
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experimental part
p. 2476 - 2484
(2012/06/30)
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- Effects of structure dissymmetry on aggregation behaviors of quaternary ammonium gemini surfactants in a protic ionic liquid EAN
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The aggregation behaviors of a series of dissymmetric cationic Gemini surfactants, [CmH2m+1(CH3)2N(CH 2)2N(CH3)2CnH 2n+1]Br2, designated as m-2-n (with a fixed m + n = 24, m = 16, 14, 12) have been investigated in a protic ionic liquid, ethylammonium nitrate (EAN). Surface tension, polarized optical microscopy (POM), small-angle X-ray scattering (SAXS), and rheological measurements are adopted to investigate the micellization and lyotropic liquid crystal (LLC) formation. The obtained results indicate that the structure dissymmetry plays an important role in aggregation process of m-2-n. With increasing degree of dissymmetry, the critical micellization concentration, the maximum reduction of solvent surface tension, and the minimum area occupied per surfactant molecule at the air/EAN interface all become smaller. The thermostability of formed LLCs is therefore improved because of the more compact molecules. These characteristics can be explained by the enhancement of solvophobic effect due to the increased structure dissymmetry of Gemini surfactants.
- Wang, Xudong,Li, Qintang,Chen, Xiao,Li, Zhihong
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p. 16547 - 16554
(2013/02/23)
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- Ionic liquid promoted synthesis, antibacterial and in vitro antiproliferative activity of novel α-aminophosphonate derivatives
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Ionic liquid ethyl ammonium nitrate is used as an excellent catalyst and solvent for three-component one-pot reaction of an aldehydes, amines and diethylphosphite to form novel α-aminophosphonates at room temperature. Among the various catalysts, the preparation of ethyl ammonium nitrate is an environmental friendly, cost effective and recyclable catalyst. Compounds 4b, 4c, 4d, 4f and 4j were found more potent antibacterials against pathogenic microorganisms. Whereas, compounds 4a, 4g, 4h and 4j inhibits growth of active Escherichia coli NCIM 2645 and Salmonella typhi NCIM 2501. Compound 4j was found a promising antiproliferative agent against A549 and SK-MEL2 human melanoma cell lines.
- Dake, Satish A.,Raut, Dnyaneshwar S.,Kharat, Kiran R.,Mhaske, Rooth S.,Deshmukh, Satish U.,Pawar, Rajendra P.
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experimental part
p. 2527 - 2532
(2011/06/17)
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- Building heterocyclic systems with RC(OR)2+ carbocations in recyclable bronsted acidic ionic liquids: Facile synthesis of 1-substituted 1H-1,2,3,4-tetrazoles, benzazoles and other ring systems with CH(OEt)3 and EtC(OEt)3 in [EtNH 3][NO3] and [PMIM(SO3H)][OTf]
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1-Aryl/alkyl-1H-1,2,3,4-tetrazoles can conveniently be synthesized in one-pot reactions from the corresponding amines by reaction with TMSN 3 and CH(OEt)3 using the readily available, recyclable, Bronsted acidic ionic liquids [EtNH3][NO3] IL-1 and [PMIM(SO3H)][OTf] IL-2 under mild conditions in high yields. Based on comparative reactions, whereas both ILs are excellent promoters, reactions are completed with shorter reaction times and in higher yields with IL-2. Among 24 examples provided, identical products were obtained via the two ILs, except in the case of 2-aminobenzoic acid where tetrazole was formed with IL-2 and 2-ethylquinazolin-4(3H)-one was formed with IL-1. By leaving out TMS-N 3 from the reaction, the in-situ formed CH(OEt)2 + and EtC(OEt)2+ (via their corresponding orthoesters) react under sonication with o-phenylenediamine bearing various substituents, o-aminothiophenol and o-aminophenol to form a wide array of benzazoles (benzimidazole, benzothiazole and benzoxazole) and quinazolin-4(3H)-one in high yields (18 examples). The two ILs reacted differently in reaction with 2-aminobenzamide, whereas quinazolin-4(3H)one was formed with IL-2/CH(OEt)3, the "unexpected" N-ethylquinazolin-4(3H)one was isolated with IL-1/CH(OEt)3. The latter was also formed from 2-aminobenzoic acid in IL-1/CH(OEt)3. Mechanistic implications are addressed. The reported protocols enable rapid assembly of a host of heterocyclic systems in high yields with the added advantage of recycling and re-use of the ILs.
- Aridoss, Gopalakrishnan,Laali, Kenneth K.
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experimental part
p. 2827 - 2835
(2011/06/23)
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- Nucleophilic and acid catalyst behavior of a protic ionic liquid in a molecular reaction media. Part 1
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This work presents a new approach using ionic liquids, namely ethylammonium nitrate. The aim was to analyze how the addition of small amounts of a protic ionic liquid to a pure molecular solvent, modifies the microscopic characteristics of a reaction medium. In order to achieve this, a kinetic study of nucleophilic aromatic substitution reactions between 1-fluoro-2, 4-dinitrobenzene and 1-butylamine or piperidine was developed in this type of binary mixtures. We have detected nucleophiles competition originated by the presence of the ionic solvent at very low concentrations, observing the ethylamine derivative as the main substitution product. Moreover, in the light of previous results we have confirmed that the protic ionic liquid can act as both Broensted acid and/or nucleophile. In this connection, we have selected the nucleophilic addition of amines to carbonyl compounds as reaction model. The protic ionic liquid in the presence of aromatic aldehydes substituted by electron-donating groups makes possible the formation of the corresponding imines with good yields. The results demonstrated that the influence of the protic ionic liquid is very important in the course of both reaction systems. Copyright
- Adam, Claudia G.,Fortunato, Graciela G.,Mancini, Pedro M.
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experimental part
p. 460 - 465
(2010/04/30)
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- PROPRIETES PHYSICOCHIMIQUES DES MELANGES EAU-NITRATE D'ETHYLAMMONIUM FONDU, A 298 K ECHELLES D'ACIDITE - SOLUBILITES
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Ethylammonium nitrate (NEA) is a protic fused salt at room temperature.It is miscible with water, at 298 K, in the whole range of mixtures.The acido-basic behaviour of water-NEA mixtures have been studied by mean of potentiometric measurements using a glass electrode, and spectrophotometric measurements using acido-basic dyes.Solubilities of non ionic compounds, (iodine, 3-nitroaniline, 2,4-dinitrophenylamine), have been determined in all water-NEA mixtures and in pure NEA.Linear free energy relationships between solubilities have been found to be valid for those media.Values of the solvent parameter g(S) has been deduced from those measurements.The "solubilizing power" of pure NEA toward non ionic compound is equal to that of a water-methanol at 70 percent by weight of alcohol, or water-dioxan at 45 percent by weight of dioxane.
- Benlhima, N.,Lemordant, D.,Letellier, P.
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p. 1919 - 1940
(2007/10/02)
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- **1 H NMR STUDY OF SOLID ETHYLAMMONIUM AND PROPYLAMMONIUM NITRATES. CATION MOTIONS IN THE STABLE AND METASTABLE PHASES.
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The **1H-NMR spin lattice relaxation times, T//1, were observed for ethylammonium nitrate, (CH//3CH//2NH//3)NO//3, and propylammoniumnitrate, (CH//3CH//2CH//2NH//3)NO//3, and for their partially deuterated analogs, (CH//3CH//2ND//3)NO//3, and CH//3(CH//2)//2ND//3NO//3, respectively. For each salt two solid phases were found, one of them being metastable and existing below ca. 200 K and ca. 210 K for the ethylammonium nitrate and propylammonium nitrate, respectively. The results of the T//1 measurements are consistent with the assumption that CH//3 and NH//3 group reorientations about their C-C and C-N bond axes take place in the stable and in the metastable phase of both salts.
- Ishida, Hiroyuki,Weiss, Alarich
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- Proprietes volumiques du nitrate d'ethylammonium fondu a 298 K et de ses melanges avec l'eau
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Partial molar volumes of water and ethylammonium nitrate EAN are determined accurately in all water-EAN mixtures, between pure water and pure fused salt at 298 K.It has been found that the partial molal volume of water decreases linearly with molar fraction of salt, x, in concentrated solution of EAN (C>2 mol L-1, x>0.04).The main thermodynamic relations are established to describe the volumetric behaviour of salt, water, and solution.It has been shown that the intrinsic volume of salt can be identified roughly with the molar volume of the pure fused salt and the value of apparent molar volume of water with the actual volume of water in solution.
- Hadded, M.,Biquard, M.,Letellier, P.,Schaal, R.
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p. 565 - 570
(2007/10/02)
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