Showing papers on "Ionic liquid published in 1976"

Equilibria between pyranoses and furanoses. IV. 1-Deoxyhexuloses and 3-hexuloses

Abstract: The equilibrium compositions of 1-deoxy-D-fructose, 1-deoxy-L-sorbose, 1-deoxy-L-psicose, D-threopentulose, D-arabino- and L-xylo-3-hexulose and coriose in aqueous solution have been determined by 13C N.M.R. spectroscopy. In all but the last case, considerable amounts of the acyclic keto form are present at equilibrium. The hydrated keto form was not detected; a model compound, l-deoxy- 3,4,5,6-tetra-O-methyl-D-fructose, was found not to be hydrated in aqueous solution.

Organometallic compounds in synthesis. VIII. Carbon-13 nuclear magnetic resonance spectroscopic study of tricarbonylcyclohexadienyliron salts

Abstract: The carbon-13 N.M.R. spectra of eleven substituted tricarbonylcyclohexadienyliron salts (1) have been determined and individual resonances assigned. Substituent effects have been deduced and compared with corresponding effects in cyclohexadienyl cations. The structures of the tricarbonylcyclohexadienyliron salts are discussed with reference to chemical shift data. The proportions of irreversible nucleophilic attack at the terminal positions in the unsymmetrical 2-substituted salts are compared with the observed chemical shifts at these carbon atoms.

Zirconium(IV) carboxylates

Abstract: Zirconium(IV) carboxylates, Zr(OOCR)4 where R = Me, Et, CH2Cl2 CHCl2 and CCl3, have been prepared by the reaction of zirconium(IV) chloride and carboxylic acids. The compounds have been characterized by elementary analyses, thermogravimetry and infrared spectral data. The compounds are non-electrolytes in nitrobenzene and probably have polymeric structures.

Radius-ratio effects in the structure of fluids of charged hard spheres

Abstract: The mean spherical model for a binary fluid of charged hard spheres with arbitrary radii has been solved numerically. The results are used to illustrate several aspects of the dependence of the structure of an ionic liquid on the relative sizes of the ionic components.

Volatility studies of metal chelates. I. Thermal studies of vanadium β-diketonates

Abstract: The complexes of vanadium(111) and oxovanadium(1V) with pentane-2,4-dione; l,l,l-trifluoropentane-2,4-dione; 1,1,1,5,5,5-hexafluoropentane-2,4-dione; l,l,l-trifluoro-5-methylhexane-2,4-dione; l,l,l-trifluoro-5,5-dimethylhexane-2,4-dine 1,1,1,2,2-pentafluoro-6,6-dimethylheptane-3,5-dione and 1,1,1,2,2,3,3-heptafluoro-7,7-dimethyloctane-4,6-dione have been prepared. The volatility, thermal and chemical stability of the chelates have been examined by simultaneous differential thermal and thermogravimetric analysis in dynamic atmospheres of nitrogen, air and water-saturated nitrogen and air, in addition to heating under vacuum to temperatures approaching 360°C. The vanadium(111) chelates of the fluorinated β-diketones volatilized with little evidence of decomposition even in air and were stable in the absence of air to 280-320°C. In contrast, the oxovanadium(1V)chelates partly decomposed during volatilization at temperatures as low as 150°C, and completelydecomposed over the temperature range 180-240oC.

Conformations of Vinyl Formate and Vinyl Acetate

Abstract: Ab initio molecular orbital theory has been used to deduce the preferred gas-phase conformations of vinyl formate and vinyl acetate. In addition, experimental dipole moments (1030μ/Cm) and molar Kerr constants (1027mK/m5 V-2 mol-1) at 25oC are reported for both molecules as solutes in carbon tetrachloride: vinyl formate (5.07, + 48.1) and vinyl acetate (5.70, + 3.8). The preferred solution-state conformations indicated by the analysis of these results are shown to be consistent with the theoretical predictions.

Frequency-dependent conductivity of ionic liquids and superionic conductors

Abstract: The frequency-dependent ionic conductivities of molten AgCl, AgBr and AgI have been measured in the far-infrared (15-300 cm-1). The results can be satisfactorily described by a simple phenomenological model which is based on the memory-function approach. Qualitative agreement is found between our experiments on molten silver halides and computer experiments on molten alkali halides. In the solid superionic conductor alpha -AgI a pronounced restrahl resonance was found. Remnants of this resonance still exist in the liquid state, but oscillation and diffusion occur on the same timescale. Superionic conductors of the AgI type thus occupy an intermediate position between an ordered ionic solid and an ionic liquid.

The radiation-induced grafting of vinylpyridines to cellulose. I. The effect of solvent structure

Abstract: A wide range of solvents have been examined for the radiation-induced grafting to cellulose of 2- and 4-vinylpyridines and 2-methyl-5- vinylpyridine by the mutual irradiation technique. The presence of a functional group containing a nitrogen and/or oxygen atom in the solvent is important for high grafting efficiency. The two most favourable groups are NH2 and OH, the former being the more effective. Inclusion of both groups in suitable positions in the one molecule, the aminoalkanols in particular (e.g. 2-aminoethanol), leads to maximum effect in grafting. Heterocyclic solvents such as pyridine and 3- picoline are also useful. Other variables affecting grafting and studied in these experiments were the effect of pK, as well as swelling, wetting and dielectric strength of solvents. The effect of surface area of cellulose on copolymerization was also examined. A novel ionic mechanism for the grafting reaction involving association between solvent and monomer is proposed.

Resonance and solvent effects on absorption spectra of 2-nitroaniline derivatives

Abstract: Spectral data for N-methyl-2-nitroaniline correlate well with those for N,N-dimethyl-2-nitroaniline in non-hydrogen-bonding, hydrogen-bond-accepting and amphiprotic alcoholic solvents. This same pattern has been reported for N-methyl-2-nitro-p-toluidine. These results indicate that these N-methyl compounds have no hydrogen bonds with any of the solvents studied and intramolecular hydrogen bonding predominates. In the N.M.R. spectra of such amines, long-range coupling between the H5 (ring) and N-H protons is not necessarily evidence for intramolecular hydrogen bonding. +M substituents at the 4-position increase the twist of the dimethylamino and 2-nitro groups and enhance the C1 → C2 transition, an effect which follows the order of +M abilities of the 4-substituents.

Volatility studies of metal chelates. II. Gas chromatographic properties of vanadium β-diketonates

Abstract: The gas chromatographic elution behaviour is reported for a total of 16 vanadium(111) and oxovanadium(1V) fluorinated β-diketonates on a column consisting of a lightly loaded, non-polar stationary phase and diatomite support. The superiority of the vanadium(111) chelates is shown to include electron-capture detection. Detection limits of 14 chelates are given for the flame ionization detector. Separation of the two oxidation states of a metal by gas-liquid chromatography is demonstrated for the first time.

Corresponding states theory for the fusion of ionic crystals

Abstract: Empirical deviations from a general thermodynamic-reduced equation of state for the orthobaric melting temperatures of alkali metal halide crystals are interpreted. A corresponding states analysis based upon reduced variables for the interaction potentials between ions shows that two limiting laws are obeyed. When the anion/cation radius ratio approaches unity the characteristic corresponding reduced length is proportional to the sum of ionic radii, but when this ratio is large, e.g. Li salts, the radius of the anion becomes the appropriate reduction parameter. The large difference in reduced melting temperatures between common-cation conformal groups can be understood by means of a first order perturbation treatment for the contribution of ion-induced dipole and short-range anion-anion iliteractions to the free energy difference between the crystalline and liquid phases of a reference salt in which these potentials are considered to be absent. Potential energy contributions due to nonconformable perturbations are found to be relatively small; this explains the observed phenomenological conformality among all the molten alkali metal halides, and many other ionic liquids, for both thermodynamic properties and linear transport coefficients.

Catalysed gas phase decompositions. XXX. Cyclopropane and boron tribromide

Abstract: Reduction of 3-furoic acid by lithium in ammonia at -33\" proceeds with 8-elimination and ring opening and consumption of four equivalents of metal to give (3) and (4). Other products (1) and (2) have been observed from reduction in the presence of a proton source. Miwa and coworkers1 have recently reported the reduction of 3-furoic acid under classical Birch conditions (sodium-ammonia-alcohol). The products isolated were acetals of type (1) formed by acid-catalysed addition of alcohol to the reduction product (2) on w0rkup.l We now find that when no proton source is present, 3-furoic acid consumes four equivalents of lithium at 33\" giving, on quenching with ammonium chloride, the hydroxy lactone (3) characterized by its spectral data, as well as its 2,4-dinitrophenylhydrazone deri~ative.~ Ethoxy lactones (4) were also isolated in varying amounts; they result from the workup conditions (continuous extraction into CHC1, from the acidified reaction mixture). The ethers (4) showed two g.1.c. peaks in the ratio of 2 : 1 but their separation and purification was precluded by the ready conversion of the pure isomers into an equilibrium mixture. The chemistry of both (3) and (4) has been discussed in some detail.2 The presumed reaction pathway is shown in Scheme 1. As shown by Miwa' the reduction takes place as for an isolated a,/?-unsaturated acid. We feel the difference in the reaction course lies in the relative rate of protonation of the dianionic intermediate (5) by alcohol as opposed to ammonia (the presumed proton source in our system); the basicity of (5) contrasts to the corresponding dianion from benzoic acid which is Kinoshita, T., Miyano, K., and Miwa, T., BUN. Chem. Soc. Jpn, 1975, 48, 1865. Salmon-Legagneur, F., and Le Goff, Y., Bull. Soc. Chim. Fr., 1965, 1761. Short Communications protonated relatively slowly in the presence of methanoL3 There is precedent in the literature for p-elimination of the ether grouping4 under our conditions.

Reduction by dissolving metals. XXI. Some deuteroanisoles

Abstract: The reversibility of the protonation steps in the metal-ammonia reduction of anisole has been investigated. Use of deuterated substrates has indicated that the product, in this case, is determined by kinetic protonation at both stages.