Solvent salts

Liquid ammonia, which boils at 240 K, is an ionising solvent. Salts are less ionised in liquid ammonia than they are in water but, owing to the lower viscosity, the movement of ions through liquid ammonia is much more rapid for a given potential gradient. The ionisation of liquid ammonia... 

In France, Compagnie Europnene du Zirconium (CEZUS) now owned jointly by Pechiney, Eramatome, and Cogema, uses a separation (14) based on the extractive distillation of zirconium—hafnium tetrachlorides in a molten potassium chloride—aluminum trichloride solvent at atmospheric pressure at 350°C. Eor feed, the impure zirconium—hafnium tetrachlorides from the zircon chlorination are first purified by sublimation. The purified tetrachlorides are again sublimed to vapor feed the distillation column containing the solvent salt. Hafnium tetrachloride is recovered in an enriched overhead fraction which is accumulated and reprocessed to pure hafnium tetrachloride. 

Zirconium and hafnium are separated by fractional distillation of the anhydrous tetrachlorides in a continuous molten solvent salt KCl—AlCl system at atmospheric pressure (56,57). Zirconium and hafnium tetrachlorides are soluble in KCl—AlCl without compound formation and are produced simultaneously. 

Chemical kinetics is the study of the rates of chemical reactions. Its practice entails the measurement of concentrations as a function of time. These measurements are extended to other variables, such as the concentrations of additional species, pH, temperature, pressure, isotopic substitution, solvent, salt concentration, and so on. 

Pyroredox. This is a three-step plutonium purification process ( 3). Impure plutonium metal is reacted with ZnCl2 in a solvent salt of KC1-CaCl 2 > as follows ... 

The simplest systems would be used, meaning that a single solvent salt with a single compatible reducing agent would be used in every process. 

In the preceding chapter the formation of the less stable of two isomeric acids on rapid neutralization of an organometallic compound was explained in terms of a free ion or ion pair as the reagent. The compounds involved were the salts of comparatively strong acids, however, and the media were highly polar. The ion or ion pair would be less likely to be the reagent in the case of the salt of a very weak acid, such as an alkyl lithium compound, in a non-polar solvent. Salts of unsaturated but weak acids might exist in either of two partly covalent forms this possibility provides an alternative explanation for the formation of the less stable of the two isomeric acids on neutralization. Presumably the bulk of the covalent or partly covalent... 

Another type of ternary electrolyte system consists of two solvents and one salt, such as methanol-water-NaBr. Vapor-liquid equilibrium of such mixed solvent electrolyte systems has never been studied with a thermodynamic model that takes into account the presence of salts explicitly. However, it should be recognized that the interaction parameters of solvent-salt binary systems are functions of the mixed solvent dielectric constant since the ion-molecular electrostatic interaction energies, gma and gmc, depend on the reciprocal of the dielectric constant of the solvent (Robinson and Stokes, (13)). Pure component parameters, such as gmm and gca, are not functions of dielectric constant. Results of data correlation on vapor-liquid equilibrium of methanol-water-NaBr and methanol-water-LiCl at 298.15°K are shown in Tables 9 and 10. 

The coupling effects of solvent/salt on electrolyte stability can also be observed when mixture solvents are used, and the stability of the electrolyte can be much improved when a stable solvent/salt is selected. For example, the room-temperature breakdown voltage of electrolytes LiX/EC/DEE lies in the order " ... 

In asymmetric hydrogenation of olefins, the overwhelming majority of the papers and patents deal with hydrogenation of enamides or other appropriately substituted prochiral olefins. The reason is very simple hydrogenation of olefins with no coordination ability other than provided by the C=C double bond, usually gives racemic products. This is a common observation both in non-aqueous and aqueous systems. The most frequently used substrates are shown in Scheme 3.6. These are the same compounds which are used for similar studies in organic solvents salts and esters of Z-a-acetamido-cinnamic, a-acetamidoacrylic and itaconic (methylenesuccinic) acids, and related prochiral substrates. The free acids and the methyl esters usually show appreciable solubility in water only at higher temperatures, while in most cases the alkali metal salts are well soluble. 

Environmentally friendly sustainable gas-solid and solid-solid or intrasolid thermal reactions proceed with 100% yield without side products. Simple couple products such as H2O, or gases or inorganic salts, can be removed without application of solvents (salts may alternatively be washed out with water). In all of these cases genuine solvent-free reactions or syntheses are achieved with unsurpassed atom economy, as these do not require purifying workup (such as... 

Following an introductory section on the historical background that has led to the development of RPC techniques as practiced today, the principles and theory of RPC will be discussed, incorporating the role of amino acid sequence and hierarchical structural effects that determine the outcome of the interaction of a peptide(s) with various types of nonpolar chromatographic surfaces. Subsequently, the influence of operating parameters such as the effects of different (1) surface morphologies or chemistries of nonpolar sorbents (2) concentrations of organic solvents, salts, or other mobile-phase additives (3) pH conditions or... 

Surface Tension Effects Mediated by Solvents, Salts, and Detergents and Their Consequences on the Resolution of Peptides by Reversed-Phase... 

The derived X-ray data indicate that the solvent-salt region in the crystals is in part not crystalline, and this is consistent with fast diffusion of small molecules into the crystals. 

In identifying the species in this biopolymer solution, we are following the convention of allocating odd numbers to low-molecular-weight components (solvent, salts) and even numbers to the polymeric components. So, for this system of biopolymeri + biopolymer2 + solvent, there is no component labelled number 3. 

This technique involves producing a solution of PLA in a solvent. Salt particles are added. As the solvent evaporates, the salt particles become imbedded in the polymer mass. Soaking the polymer in water dissolves the salt and voids remain. 

The other type is ion-conducting solids [polyethylene oxide) + salt] or gels (polymer + solvent + salt) (p. 314). 

In the present study, systems composed of two solvents and a salt are treated as ternary systems. Data on the vapor pressure depression of the solvent by the salt for isothermal systems and on the boiling point elevation of the solvent in the presence of salt for isobaric systems are used to develop the parameters for the solvent-salt binaries. For such binaries only the activity coefficients for the solvent are considered. The parameters for all three binary sets are generated from the binary data by a regression subroutine. 

The Wilson equation was considered first. Great problems were encountered with this equation. Negative values for one or both of the parameters A12 and A21 were often obtained by regressing the solvent-salt data. As it can be seen from Equation 3, a negative value for Aij is unacceptable. 

Turning now to the solvent-solvent binary, the effect of the value of a 2 on the quality of the obtained fit is well established (12,16). Since this binary had the largest number of experimental activity coefficients—for the solvent-salt binaries only the y of the solvent is used—it was decided to let a vary between +1.0 and —3.0 with the best fit of the ternary data as criterion for its optimum value. The possibilities of varying the other two as (ai3 and 23) to obtain the best ternary fit was rejected although it would probably lead to better correlation of the ternary results, it could not lead to any predictive scheme. The number of available systems is simply too limited for the establishment of optimum a values for all three binaries. 

Leaching The dissolution and extraction of chemical species from solid samples by water, acids, bases, organic solvents, salt solutions, or other liquids (compare with batch leaching, column leaching, sequential batch leaching, serial batch leaching, and leaching test). 

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