Salts as electrolytes

Electrochemical oxidation of 4-aryl-substituted thiane in aqueous organic solvents containing various halide salts as electrolytes gave selectively the trans-sulfoxide (lOe). Under acidic conditions a preferential formation of the cis-sulfoxide was attained328. The stereoselective potential of this method for the oxidation of cyclic sulfides139,329 is apparent (equation 123). 

Electrolytes for Lithium-Based Rechargeable Batteries Table 3. Lithium Salts as Electrolyte Solutes... 

The addition of carbanions, generated electrochemically by reduction of the carbon-halogen bond, to carbon dioxide has been examined under a variety of experimental conditions. Direct electrosynthesis of carboxylic acids in a divided cell using an aprotic solvent and a tetraalkylammonium salt as electrolyte is most sue-... 

Pt2(P205H2)4, also known as Pt2(POP)4, in the presence of tetrabutylam-monium (TBA) salts as electrolyte [19,20], ECL has also been observed from palladium and platinum a, 3,y,5-tetraphenylporphyrin complexes, and also via self-annihilation of the electrogenerated anion and cation radicals [21],... 

The electrochemical generation of hydrogen in aqueous acid or alkaline solutions reduces unactivated alkynes 46 a b). This process is similar to catalytic hydrogenation, however, and does not involve electron transfer to the substrate. The electrochemical generation of solvated electrons in amine solvents or HMPA has also been effective in reducing these compounds 29). The focus of this section, however, is the electrolysis of these difficult to reduce alkynes and alkenes at mercury cathodes with tetraalkyl-ammonium salts as electrolytes. Specific attention is also given to competitive reductions of benzenoid aromatics and alkynes or alkenes. 

The last entry of table 1, tetrahexylammonium benzoate, is an example of the use of molten salts as electrolytes. In this particular case, the salt is liquid at room temperature, but it has been reported that tetrabutylammonium nitrate at 150° can be used for polarographic and preparative work 7Sa-> (oxidation of polycyclic aromatic hydrocarbons). The use of molten salts as SSE s is of great interest because of the high conductivities of such media as compared to conventional SSE s and deserves further studies. 

A battery which uses room temperature molten salts as electrolyte could... 

Electrochemical methods for the reduction of aromatic substrates utilizing ammonia and amines as solvents with lithium salts as electrolytes have been successful. Toluene was reduced to the 2,5-dihydro derivative in 95% yield in methylamine-lithium chloride if an undivided cell was used, while a 53 47 mixture of 3- and 4-methylcyclohexenes was formed in a divided cell.. Of greater interest, however, are attempts to achieve these reductions in aqueous media. In one experiment utilizing a two-phase mixture of substrate in aqueous tetra-n-butylammonium hydroxide and a mercury cathode, anisole was reduced on a preparative scale (15 g) to its 2,5-dihydro derivative in 80% yield. The optimal temperature for most reductions appeared to be 60 °C and under these conditions, even suspensions of high molecular weight substrates could be successfully reduced, e.g. steroid (226) afforded a >90% chemical yield of (227). Much higher coulombic yields were obtained when a small amount of THE was added to the mixture, however. 

Difluorobenzene can be reduced to fluorobenzene, which in turn can be reduced further to benzene using constant current in diglyme with TAA salts as electrolyte [65]. The best conditions for a selective reduction to CeH F was a relative low current density (1.25 mA cm ), low concentration of (DMP)BF4 (0.01 M-I-O.IM TBABF4), and low water concentration (0.5%). 

The micFobiologically important 4-oxoquinoline-3-carboxylic acid skeleton is formed by applying Dieckmann conditions to the diester (70.9) in which the NH is protected as its acyl derivative. Dehydrogenating agents such as chloranil do not always give good results when applied to the dihydroquinolinones thus produced. Better yields are obtained by electrolysis in acetic acid-t-butanol with a quaternary ammonium salt as electrolyte. With careful choice of conditions, a high yield of the deacylated quinolinone may be obtained. 

FIGURE 2.17 Comparison of molar conductivity (at 0.05 M) of SiWA salts and other common salts with the same counter cations. (Reprinted from Electrochimica Acta, 138, Gao, H., A. Virya, and K. Lian, Monovalent silicotungstate salts as electrolytes for electrochemical supercapacitors, 240-246, Copyright 2014, with permission from Elsevier.)... 

Gao, H., A. Virya, and K. Lian. 2014. Monovalent sUieotungstate salts as electrolytes for electrochemical supercapacitors. Electrochimica Acta 138 240-246. 

O. E. Geiculescu, Y. Xie, R. Rajagopal, S. E. Creager, D. D. DesMarteau, J. Huor. Chem. 2004, 125, 1179-1185. Dflithium bis[(perfluoroalkyl)sulfonyl]diimide salts as electrolytes for rechargeable lithium batteries. 

L. Yang, H. Zhang, P. F. DriscoU, B. Lucht, J. B. Kerr, ECS Trans. 2011, 33, 57-69. Six-membered-ring malonatoborate-based lithium salts as electrolytes for lithium ion batteries. 

Most primary or storage cells in use earlier or commercially produced at present contain aqueous solutions of alkalis, acids or salts as electrolytes. It can be said that the proportion of all possible electrochemical systems with aqueous electrolyte solutions have now been sufficiently thoroughly investigated and their performance can be assessed with high accuracy. On the other side properties of electrochemical systems with nonaqueous electrolytes - solutions in organic solvents, salt melts or solid electrolytes - have been studied in much less detail. It is quite likely that the characteristics of cells with these electrolytes will be... 

Poly(p-phenyleneterephthalamide) is soluble in dimethyl sulfoxide and is used to produce the well-known Aramid fibers. A blend of this material and polypyrrole in the form of film was prepared by the electrode coating method and using a / -toluenesulfonate salt as electrolyte [82]. A comparison of the mechanical properties of the blend with pure polypyrrole showed that the blend is a tougher material with a higher modulus and lower elongation at break. Treatment of the blend with HCl raises the conductivity but also increases hardness and toughness. 

Molten carbonate fuel cells (MCFC) are composed of a porous nickel-based anode, a porous nickel oxide-based cathode and molten carbonate salts as electrolyte within a porous lithium aluminate matrix. Molten carbonate fuel cells with internal reforming can be fed directly with light hydrocarbons rich gas such as... 

The alkali metals lithiirm and sodium are attractive as battery anodes on account of their high electrode potentials and their low atomic masses, which together result in excellent values for the battery specific energy. In this chapter we consider batteries which utilize solids (fast ion conductors) or fused salts as electrolytes and which operate at temperatures of 200 to... 

When natural gas is considered as a possible fuel, an increase in the rate of the electrode reactions is needed. Since catalysts are either very expensive or unknown, temperature is raised to lower the overpotential. Since the products of oxidation of natural gas are carbon dioxide and water, these will always be present in the gas mixture over the cell. An equilibrium between the gases and the molten salt electrolyte will be established, and part of the electrolyte will be converted to carbonate, regardless of the nature of the original anion. Therefore, it seems reasonable to use molten carbonates, not other salts, as electrolytes. On the other hand, since carbonates dissociate at high temperatures to give carbon dioxide, it is necessary to keep the partial pressure of CO2 above the cell at such a value as to retard any change in the composition of the electrolyte. Both the fuel gas and the air are premixed with carbon dioxide before being fed to the fuel cell. 

Zaidi W, Boisset A, Jacquemin J, Timperman L, Anouti M (2014) Deep eutectic solvents based on N-methylacetamide and a lithium salt as electrolytes at elevated temperature for activated carbon-based supercapacitors. J Phys Chem C 118(8) 4033-4042. doi 10.1021/ jp412552v... 

Table 11.3 Lithium salts as electrolyte solutes [1] with L1BF4 lithium tetrafluoroborate, LiBF lithium hexafluorophosphate, LiAsFs lithium hexafluoroarsenate, UCIOa lithium perchlorate, Li-triflate lithium trifluoromethanesulfonate Li itnide (LiTFSI) BIS (trifluoromethane) suifonimide lithium...

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