Molten ammonium salts, quaternary

In some cases, the Q ions have such a low solubility in water that virtually all remain in the organic phase. ° In such cases, the exchange of ions (equilibrium 3) takes place across the interface. Still another mechanism the interfacial mechanism) can operate where OH extracts a proton from an organic substrate. In this mechanism, the OH ions remain in the aqueous phase and the substrate in the organic phase the deprotonation takes place at the interface. Thermal stability of the quaternary ammonium salt is a problem, limiting the use of some catalysts. The trialkylacyl ammonium halide 95 is thermally stable, however, even at high reaction temperatures." The use of molten quaternary ammonium salts as ionic reaction media for substitution reactions has also been reported. " " ... 

When sodium chloride is dissolved in water at ordinary temperatures, it is practically completely dissociated into sodium and chloride ions which, under the action of an external field, move in opposite directions and independently of each other subject to coulombic interactions. If, however, sodium chloride is dissolved in a solvent of lower dielectric constant, and if the solution is sufficiently dilute, there is an equilibrium between ions and a coulombic compound of the two ions which are commonly termed 4 ion pairs. This equilibrium conforms to the law of mass action when the interaction of the ions with the surrounding ion atmosphere is taken into account. In solvents of very low dielectric constant, such as the hydrocarbons, sodium chloride is not soluble however, many quaternary ammonium salts are quite soluble, and their conductance has been measured. Here at very low concentrations, there also is an equilibrium between ions and ion pairs which conforms to the law of mass action but at higher concentration, in the neighborhood of 1 X 10 W, or below, a minimum occurs in the conductance. Thereafter, it may be shown that the conductance increases continuously up to the molten electrolyte, provided that a suitable electrolyte and solvent are employed which are miscible above the melting point of the electrolyte. 

Reaetions no. 6 and no. 7 in Table 5-15 demonstrate that with molten quaternary ammonium salts as solvents, where deaetivation by anion solvation is absent, the halide ions show the same nueleophilie order as in dipolar non-HBD solvents [283, 284], This is in aeeordanee with the theory of protie/dipolar non-HBD medium effeets on X nueleophilieity [6j. It has been suggested that fused-salt experiments should provide a good model for the determination of intrinsie relative nueleophilieities of anions towards saturated earbon atoms [284],... 

Jn a potentially far reaching application for melt catalysis by the transition metals, we at Texaco have demonstrated the synthesis of a range of commodity chemicals and fuels directly from CO/H2 via the use of ruthenium-containing molten salt catalysis. Products include ethylene glycol, Ci-C4 alcohols, acetic acid, acetate esters, C2+ olefins and vicinal glycol esters. In its simplest form, this new class of melt catalyst comprises one or more ruthenium sources, e.g. ruthenium carbonyls, oxides, complexes, etc. dispersed in a low-melting (m.p. <150 C) quaternary phosphonium or ammonium salt (e.g. tetrabutylphos-phonium bromide). The key components are selected such that ... 

Catalyst-philic liquid phases can be used to promote the catalytic activity of heterogeneous catalysts, and to facilitate product-catalyst separation. A variety of different constituents of such catalyst-philic phases can be used, the most attractive being quaternary ammonium and phosphonium salts, PEGs, as well as water and other kinds of low-temperature molten salts. In each system, the catalyst-philic phase is characterized as being separate from the remainder of the reaction mixture, and the catalyst should reside within this phase. 

Sun, J., Forsyth, M., MacFarlane, D. R., Room-temperature molten salts based on the quaternary ammonium ion, /. Phys. Chem. B., 102,8858-8864,1998. 

Figure 2.3 TgScaled Arrhenius plot showing data for molten salts ZnCl2 and calcium potassium nitrate (CKN), with data for the calcium nitrate hydrate (CaNOs-W ) and the tetrafluoroborates of quaternary ammonium (MOMNM2E, M= methyl, E = ethyl) and 1-n-butyl-3-methyl-imidazolium (BMI) cations, and the bis-oxalatoborate (BOB) of the latter cation, in relation to other liquids of varying fragility (from Xu, Cooper, and Angell [15]).

The hydrofluoric acid based molten salts such as quaternary ammonium cations and F(HF) anions have a low viscosity and are used as an electrochemical fluorination bath [17]. Hagiwara et al. reported new RTILs with a low viscosity based on the... 

Matsumoto, H. Miyazaki, Y. Ishikawa, H., Japan Patent Kokai 1999-297355 1999. Matsumoto, H. Yanagida, Y Tanimoto, X Kojima, Y. Tamiya, Y Miyazaki, Y., Improvement of ionic conductivity of room temperature molten salt based on quaternary ammonium cation and imide anion, In Molten Salts XII Proceedings of the International Symposium, Trulove, P.C. De Long, H. C. , Stafford, G. R. Deki, S., Ed. The Electrochemical Society Proceeding Series, The Electrochemical Society, Pennington, NJ, 2000 PV99-41, 186-192. 

Mizuhata, M., Maekawa, M. and Deki, S., Ordered structure in room temperature molten salts containing aliphatic quaternary ammonium ions, ECS Trans. 3, 89-95 (2007). 

Temperature Molten Salts Based on the Quaternary Ammonium Ion. 

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