Showing papers on "Ionic liquid published in 1975"

Solvation of ions. XXV. Partial molal volumes of single ions in protic and dipolar aprotic solvents

Abstract: Partial molal volumes at 25° are reported for some 1 : 1 electrolytes, and for triphenylmethane, in dimethyl sulphoxide, N,N- dimethylformamide, acetonitrile, propylene carbonate, formamide and hexamethylphosphoramide. The assumption that ΔV°tr(Ph4As+) = ΔV°tr(BPh4-) was used to obtain ionic partial molal volumes of transfer from water to the non-aqueous solvents. Solvent compressibility appears to determine the partial molal volumes of non-electrolytes and large hydrophobic ions in solution. Values of ΔV°tr for cations and anions are discussed in terms of ion-solvent interactions, solvent-solvent interactions and steric crowding of large solvent molecules around the ions.

The reduction of HCl dissolved in LiCl-KCl eutectic

Abstract: The cathodic reduction of hydrogen chloride dissolved in LiCl-KCl eutectic has been studied by both chronopotentiometry and linear sweep voltammetry using a platinum electrode. The reduction reaction has been found to proceed by a reversible one-electron transfer process forming a soluble product. Diffusion coefficients calculated from solubility measurements and the electrochemical studies are considerably higher (e.g. 2.1 x 10-4 cm2 s-1 at 793 K) than most other solutes in molten salts but in good agreement with results from a less detailed study. The high value is probably due to the small ionic radius of the proton as compared to other ions in the lattice of the molten salt system.

Corresponding-states correlation of properties of ionic melts

Abstract: Aspects of the corresponding-states correlation of certain properties of ionic liquids and liquid mixtures are examined. The results of Monte-Carlo computations are used to show that an interionic potential to which corresponding-states theory can be rigorously applied is insufficiently flexible to account for details of the thermodynamic properties of molten alkali-metal salts. The specific model studied is one frequently referred to in discussions of the application of dimensional methods in the statistical mechanics of ionic salts. Use of the same idealized potential model in the case of mixtures leads to values of the excess thermodynamic properties which are consistent with the predictions of conformal solution theory but differ qualitatively from those observed experimentally. The possibility of using results obtained by computer simulation to extend the range of validity of existing corresponding-states relations is discussed and the example of ionic diffusivity is treated as an illustration.

Molecular Dynamics Calculations on Molten Ionic Salts

Abstract: The advent of computers in recent years has given considerable impetus to progress in many areas of physical science. This article reviews some aspects of the application of modern computer simulation techniques to studies of the physical chemistry of molten salts.

Cyclometallation reactions. XIV. Some reactions of nitrogen-donor ligands

Abstract: The preparation of ortho-metallated complexes from reactions between MnR(CO)5 (R = Me or CH2Ph) or Li2PdCl4 and the following N-donor ligands is reported: azophenetole [Mn; also Ru, from Ru3(CO)12], Dimethyl Yellow (Pd), 4,4?-azobis(N,N-dimethylaniline) (Mn,Pd), azoxybenzene (Pd), 4,4?-azoxyanisole (Pd), benzylideneazine (Mn), N,N?-dimethylbenzylamine (Mn) and N-benzyl-aniline (Mn). The reactions between MnMe(CO)5 and azoxybenzene and azoxyanisole afford metallated derivatives of the corresponding azo compounds; the former derivative was also obtained from hydrazobenzene and MnMe(CO)5.

Structure of aqueous solutions: Infrared spectra of the water librational mode in solutions of monovalent halides

Abstract: The variations of the infrared librational mode of water with concentration of added salt have been examined at 30°C for solutions of NH4F, NH4Cl, NH4Br, NH4I, LiCl, LiBr, NaCl, NaBr, NaI, KCl, KBr and KI. The data indicate that water in the primary hydration sheath can be distinguished from the remainder of the water and primary hydration numbers have been estimated. It is shown that in general the larger the ion the greater the change to the spectral band. The ammonium fluoride is shown to be unique in producing little disturbance of the water structure.

Organic Reactions in Molten Tetrachloroaluminate Solvents

Abstract: The use of molten salts as a medium for organic reactions has been known since organic chemistry’s beginning. The advantages such as short reaction times, ease of product recovery, possibility of high yields, and savings on solvent recovery together with the unusual physical properties (ionic liquids, high conductivity) shown by molten salts in comparison with other solvents opens new frontiers in the study of organic syntheses, separations, and mechanisms.

The standard potential of the silver-silver bromide electrode and ion solvation in t-butyl alcohol + water mixtures at 298.15 K

Abstract: E.m.f. measurements of the cell Pt|H2|HBr(m), ButOH(X), water|AgBr|Ag have been made at 298.15 K for solvent compositions X = 10, 20, 30, 40, 50 and 70% (w/w) of t-butyl alcohol. These have been used to evaluate the standard potential of the silver-silver bromide electrode and the free energy of transfer, ΔG°t, of the acid from water to the respective solvent media. These ΔG°t values, along with those for hydrochloric acid, are briefly discussed in relation to ion solvation. Mean ionic activity coefficients of hydrobromic acid in the various solvents have also been calculated.

Gas Solubility in Molten Salts

Abstract: Interest in the solubilities of nonreactive gases in molten salts stemmed originally from the technological need developed as a consequence of gaseous fission products of radiated molten salts. A secondary technological development associated with industrial uses of molten salts as heat treatment baths, electrolytes, and metallurgical slags led to other studies of the influence of various gases and vapors on the physical and chemical properties of the fused salts. Systematic research of gaseous solutions of molten salts has lagged behind technological studies and lies considerably more dormant than analogous studies in water and organic solvents. Theoretical studies of the liquid state and solution theory, on the other hand, have been pursued which provide applications to ionic liquid solvents such as the simpler molten salts.

Physico-chemical studies in non-aqueous solvents. X. Conductance and solvation studies of 1 : 1 electrolytes in N,N-dimethylacetamide

Abstract: Conductances of some 1 : 1 electrolytes have been measured in the concentration range 1-120 x 10-4 mol l-1 in N,N-dimethylacetamide at 25°. The conductance data have been analysed by Fuoss-Onsager-Skinner equations for dissociated and associated electrolytes, and limiting equivalent conductances, ion-size parameter and association constants (where appropriate) for various electrolytes have been obtained. The ion-size parameter (3.7 ± 0.3Ǻ) has been found to be about the same for all the electrolytes. Alkali metal salts are fully dissociated while the substituted ammonium salts are slightly associated in this solvent. The ionic association increases with increase in the size of cations. Transference numbers of lithium chloride, potassium thiocyanate and silver perchlorate have also been measured in the concentration range 1.1-18.4 x 10-2mol l-1 in this solvent. Limiting cation transference numbers are determined from the linear plots of cation transference numbers against square root of concentration. Ionic mobilities, effective ionic radii and solvation numbers of various ions in solution have been calculated. Higher solvation numbers of cations than those of anions of comparable sizes are consistent with the aprotic nature of the solvent.

Pyrazolidine-3,5-diones with heterocyclic substituents. III. Oxidation of 4-Monoalkylpyrazolidine-3,5-diones

Abstract: 4-Alkylpyrazolidine-3,s-diones with phenyl or 3-phenyl-1H-1,2,4- triazol-5-yl substituents on N 1 or N 2 were oxidized with oxygen or hydrogen peroxide in acidic, basic or neutral media. Conditions under which 4-hydroxypyrazolidinediones and monohydrazides of malonic or tartronic acids are formed were noted.

The effect of pressure on the rates of some substitution reactions of alkyl halides

Abstract: Measurements have been made of the influence of hydrostatic pressure on the rates of three kinds of bimolecular substitution reactions of alkyl halides in solution. They are reactions with (a) halide ions in acetone solution (Finkelstein reactions), (b) silver nitrate in aqueous ethanol and (c) mercuric nitrate in aqueous dioxan. The Finkelstein reactions were unsymmetrical with respect to the halogen atoms, for instance I- + PrCl → PrI+Cl-. They were all accelerated by an increase of pressure, in contrast to the sym- metrical exchange I*- + PrI → PrI* + I-, which is known to be retarded by an increase of pressure. This fact supports Gonikberg's view of the role of partial desolvation in the symmetrical reactions. Reactions involving LiCl as the source of halide ions were accelerated much more than those involving KI, simply because an increase of pressure enhances the dissociation of unreactive LiCl ion pairs. Reactions of the types (6) and (c) were also accelerated by an increase of pressure, a fact which argues against a suggestion that the attacking species might be ion pairs.

Chromium(III) complexes in dipolar aprotic solvents. VIII. Solvolysis of hexaisothiocyanatochromate(III) and solvent exchange, substitution and anation of the pentaisothiocyanato(solvento)chrornate(III) complex, [Cr(NCS)5(sol)]2-

Abstract: The displacement of the coordinated Me2SO from [Cr(NCS)5(Me2SO)]2- by NCS- and pyridine has been studied in the solvent tetramethylene sulphone (sulpholane). The results are consistent with a limiting dissociative mechanism. The solvolysis reactions: [Cr(NCS)6]3- + sol → [Cr(NCS)5(sol)]2- + NCS- have been studied in the solvents (sol) Me2SO, HCONMe2 and MeCONMe2. The transition states for these solvolysis reactions are compared with a dissociative model [Cr(NCS)5(3-)+(∂+)...NCS∂-] by means of solvent transfer activity coefficients. Kinetic and activation data are recorded for a number of solvent interchange reactions: [Cr(NCS)5(sol1)]2- + sol2 → [Cr(NCS)5(sol2)]2- + sol1

Thermodynamic study of the deuterium isotope effect, the molar excess enthalpies of C6D6 + c-C6H12 and of C6H6 + c-C6H12

Abstract: Molar excess enthalpies of C6D6 + c-C6H12 and of C6H6 + c-C6H12 have been measured at 298.15 K; the equimolar values are 818.7 and 797.0 J mol-1 respectively.