Showing papers on "Ionic liquid published in 1982"

The structure and electronic properties of liquid semiconductors. III. Structural evidence for ionicity in liquid Tl2Te

Abstract: For pt.II see ibid., vol.15, p.4635 (1982). The total structure factor of liquid Tl2Te has been measured by neutron diffraction and compared with the prediction in k-space of the mean spherical model of an ionic liquid consisting of Tl+ and Te2- ions. Good overall agreement is achieved. The total radial distribution function in real space has been investigated and it is concluded that models of the melt based on discrete molecules should be abandoned.

Heterocyclic ambident nucleophiles. IV. The alkylation of metal salts of adenine

Abstract: The N3 : N7 : N9 alkylation patterns for reactions of the lithium, sodium, and potassium salts of adenine with various alkylating agents in dimethyl sulfoxide were determined by 1H n.m.r. spectroscopy. Only for the Li+ salt was any significant effect of ionic association noticed. Of the alkylating agents used, only chloromethyl pivalate gave a concentration dependent alkylation pattern. The latter effect was most pronounced with the heterogeneous alkylation conditions of anhydrous Na2CO3/HCONMe2, adenine, and chloromethyl pivalate; here, increasing concentrations changed the main reaction from N7- to N9-alkylation. Solvent effects on the alkylation patterns were also studied. Within the common dipolar aprotic solvent group, (Me2N)3PO, HCONMe2 and Me2SO, effects were small; in protic solvents, particularly formamide, enhanced N3-alkylation was observed.

The surface tension of ionic liquids: A mechanical formula

Abstract: (1982). The surface tension of ionic liquids A mechanical formula. Molecular Physics: Vol. 47, No. 5, pp. 1211-1225.

An Electrochemical and Infrared Study of Chloranil in n‐Butylpyridinium Chloride:Aluminum Chloride Ionic Liquid

Abstract: : The electrochemical behavior of tetrachlorobenzoquinone (chloranil, Q) has been studied in the aluminum chloride-n-butylpyridinium chloride (BuPyC) ionic liquid system. The reduction of chloranil proceeds in a two-electron step, giving rise to the dianion. Both the electrochemistry and infra-red spectroscopy appear to indicate that, depending on the acidity of the system, chloranil is complexed by AC3, initially on the carbonyl oxygen, and on the ring chlorines. The second carbonyl appears to remain uncomplexed. Large shifts in the reduction potential for chloranil are observed as the solvent acidity (mole ratio of AC3 to BuPyc) is varied, indicating the extensive degree of interaction of the solute with the solvent. Cyclic voltammetry indicates the presence of one or as many as three species, depending on the acidity, which are concluded to be in rather slow equilibrium. Nernst plots of the potential of an indicator electrode as a function of the Q/Q= ratio indicate potentiometric reversibility; at a fixed Q/Q= ratio, the potential variation as a function of melt acidity indicates a gain of three AC3 molecules per Q= relative to Q, suggesting that it is complexed by 6 AC3 molecules in the acid system. (Author)

Electroactivity of hydrogen–nitrogen compounds in ionic liquids. Platinum rotating-disc electrode voltammetric behaviour of ammonia in the (Na, K)NO3 equimolar melt

Abstract: In the context of a systematic investigation on light-fuel electrodes in ionic solvents, the voltammetric behaviour of ammonia was studied in the (Na, K)NO3 equimolar melt at 518 K.Solutions containing NH3, NH3+ H2O, NH3+ NO–2 were tested by using platinum rotating-disc electrode systems. Mechanistic models for the electro-oxidation and electroreduction reactions of ammonia are suggested which fit the experimental electrochemical findings and, in particular, the constant value of the ratio between the electroreduction and the electro-oxidation limiting currents of ammonia. The diffusion coefficient of ammonia in the given experimental conditions was estimated to be 1.9 × 10–5 cm2 s–1 at the given temperature.The chemical behaviour of amide ions, which are involved in the ammonia electroreduction pathway, is described.‘Concealed limiting-current’ phenomena observed when ammonia is flowed in nitrite-containing melts are explained on the basis of acid–base reactions between each of these two species and the electro-oxidation product of the other.

Room Temperature Molten Salt Electrolytes for Photoelectrochemical Applications

Abstract: Mixtures of aluminum chloride (AlCl3 ) with triethylammonium chloride (Et3 NHCl), 1,6-ethyl lutidinium bromide (EtluBr), tert-butyl pyridinium bromide (BPBr), and dialkyl imidazolium chloride (R2 ImCl), in certain molar ratios yielded ionic liquids at room temperature which were studied with respect to their applicability as electrolytes in photoelectrochemical (PEC) cells. Background voltammograms were obtained for these electrolytes on carbon and n-GaAs electrodes. The anodic stability limit was found to be enhanced on n-GaAs relative to carbon in all cases. The cathodic decomposition potential of the electrolyte showed a smaller positive shift on n-GaAs with the exception of the 3:1 AlCl3 -BPBr electrolyte. The difference in electrolyte stability behavior on carbon and n-GaAs is interpreted in terms of carrier density effects. Cyclic voltammograms were compared on carbon in the various electrolytes for a model redox system comprising the ferrocene/ferricenium couple. The separation of the cathodic and anodic waves in all the cases was consistent with a quasi-reversible redox behavior—the most sluggish electron transfer being observed in the case of the 3:1 AlCl3 -BpBr electrolyte. These results are compared with those obtained previously on the AlCl3 -butyl pyridinium chloride (BPC) system. Capacitance-voltage measurements were made on n-GaAs electrodes in contact with the various electrolytes. Flatband-potentials (Vfb ) were deduced from these data using Mott-Schottky plots. The relative positions of the n-GaAs band-edges and the redox levels were mapped on a common potential scale utilizing these data. The ferrocene/ferricenium redox level was placed negative of the conduction band-edge in n-GaAs in all the cases. The implications of this result for PEC applications and the role of specific ion adsorption of electrolyte species on the electrostatic aspects of the n-GaAs/molten salt electrolyte interface are discussed with the aid of energy band diagrams.

Reactions of Aryldiazonium Salts and Alkyl Arylazo Ethers. VIII* General Acid Catalysis of the Ionization of Alkyl (E)-Arylazo Ethers in Alcoholic Solvents

Abstract: Further studies of the general acid-catalysed ionization of alkyl (E)-arylazo ethers in alcoholic solvents have been carried out. The magnitude of catalysis and the degree of proton transfer as a function of the substituent on the aromatic ring, the alkoxide ion nucleofuge, the solvent and the ionic strength have been studied. The results are consistent with a mechanism for the acid-catalysed ionization of alkyl (E)-arylazo ethers in which proton transfer and N-O bond breaking are concerted. 1H and 13C n.m.r. data for a number of alkyl p-nitrophenylazo ethers are reported.

The metal-nonmetal transition in ionic liquids

Abstract: The metal-nonmetal transition in ionic liquids is reviewed with special emphasis on alkali metal-alkali halide solutions and the ionic alloy Cs-Au. Magnetic measurements, especially nuclear magnetic resonance, are discussed in relation to the nature of localized electronic states at low concentrations of excess metal and electron dynamics in the metal-nonmetal transition region. It is suggested that the stability of non-magnetic species governs the occurrence of a continuous metal-nonmetal transition or, alternatively, liquid-liquid phase separation.