Solvent anions

Binary Electrolyte Mixtures When electrolytes are added to a solvent, they dissociate to a certain degree. It would appear that the solution contains at least three components solvent, anions, and cations, if the solution is to remain neutral in charge at each point (assuming the absence of any applied electric potential field), the anions and cations diffuse effectively as a single component, as for molecular diffusion. The diffusion or the anionic and cationic species in the solvent can thus be treated as a binary mixture. 

In this scheme DMSO is to be regarded as a solvent anion formed by an electron attachment or solvent decomposition from free or solvated electrons. Reaction 13 can be... 

This theory is associated in its early protonic form with Franklin (1905, 1924). Later it was extended by Germaim (1925a,b) and then by Cady Elsey (1922,1928) to a more general form to include aprotic solvents. Cady Elsey describe an acid as a solute that, either by direct dissociation or by reaction with an ionizing solvent, increases the concentration of the solvent cation. In a similar fashion, a base increases the concentration of the solvent anion. Cady Elsey, in order to emphasize the importance of the solvent, modified the above defining equation to ... 

The composition of the electrolyte is quite important in controlling the electrolytic deposition of the pertinent metal, the chemical interaction of the deposit with the electrolyte, and the electrical conductivity of the electrolyte. In the case of molten salts, the solvent cations and the solvent anions influence the electrodeposition process through the formation of complexes. The stability of these complexes determines the extent of the reversibility of the overall electroreduction process and, hence, the type of the deposit formed. By selecting a suitable mixture of solvent cations to produce a chemically stable solution with strong solute cation-anion interactions, it is possible to optimize the stability of the complexes so as to obtain the best deposition kinetics. In the case of refractory and reactive metals, the presence of a reasonably stable complex is necessary in order to yield a coherent deposition rather than a dendritic type of deposition. 

According to M. Blander the association constant depends on the change in the Gibbs energy, AG, during exchange of a solvent anion Y", next to a cation of the dissolved salt A+, for an anion of the dissolved salt B according to the relationship... 

As was pointed out in the introduction, the properties of the metals produced by these reduction methods are highly dependent on the various parameters of the reduction, i.e., solvent, anion, reducing agent, etc. 

The main disadvantage in using poly(acrylamide) systems is that they are not biodegradable and the monomers are toxic. Extensive purification is also required to remove the organic solvents, anionic surfactants, and residual monomers. Edman et al. [74] produced biodegradable poly(acryldextran) particles by incorporating dextran into the poly(acrylamide) chain. These particulate systems were metabolized and eliminated faster, both in vivo and in vitro, than poly(acrylamide) particles. 

Unlike many other enzymes, the subtilisins are fairly stable towards e.g. organic solvents, anionic surfactants, high temperatures and high pH. This makes the subtilisins very suitable as detergent proteases. But despite this fact, stabilization of these protease enzymes in liquid detergents remains a major issue. 

Structural Data for Compounds of the Type [R3E (solvent)][anion] ... 

Electrons in nonpolar liquids are either in the conduction band, trapped in a cavity in the liquid, or in special cases form solvent anions. The energy of the bottom of the conduction band is termed Vq. Vq has been measured for many liquids and its dependence on temperature and pressure has also been measured. New techniques have provided quite accurate values of Vq for the liquid rare gases. The energies of the trapped state have also been derived for several liquids from studies of equilibrium electron reactions. A characteristic of the trapped electron is its broad absorption spectrum in the infrared. 

Electron photodetachment upon laser excitation of the solvent anion above 1.76 eV was observed (Fig. 2a,c) [18]. The cross section of photodetachment linearly increases between 1.76 and 3 eV (Fig. 2b). Under the same physical conditions, the photodetachment and absorption spectra of the solvent anion are identical (Fig. 2b) [20], suggesting a bound-to-CB transition the quantum yield of the photodetachment is close to unity. The photodetachment spectrum is similar to the photoelectron spectra of (C02) 9 clusters observed by Tsukuda et al. [24] in the gas phase it is distinctly different from the electron photodetachment spectra of CO2 in hydrocarbon liquids [27]. This suggests that a C-C bound, 7)2, symmetric dimer anion constitutes the core of the solvent radical anion [18,19]. 

SOLVENT ANIONS IN LIQUID CS2, CgFe, AND AROMATIC HYDROCARBONS... 

Carbon disulfide is isovalent to carbon dioxide and it also has a bent monomer anion. While gas-phase CO2 has negative EAg of —0.6 eV [24], for CS2, EAg is +0.8 eV [34]. Despite this very different electron affinity, Gee and Freeman [34] observed long-lived electrons in CS2 (with lifetime > 500 psec) with mobility ca. 8 times greater than that of solvent cations. Over time, these electrons converted to secondary anions whose mobility was within 30% of the cation mobility. Between 163 and 500 K, the two ion mobilities scaled linearly with the solvent viscosity, as would be expected for regular ions. Of course, Gee and Freeman s identification of the long-lived high-mobility solvent anions as electron is just a manner of speech Obviously, quasifree or solvated electrons cannot survive for over a millisecond in a positive-EAg liquid. 

As in the case of hexafluorobenzene solvent anion, EPR and ODMR spectroscopies suggests that no dimerization of monomer radical anions of benzene and toluene occur in liquid benzene and/or in alkane solutions of benzene (whereas the radical cation of benzene is known to dimerize rapidly). The conductivity studies also indicate that there is no volume change associated with the dimerization [45]. 

UV-Vis spectra). Classifying these solvent anions as molecular ions solvated by their parent liquids or solvated electrons does not explain these properties. 

It may appear from the above that only nonpolar liquids yield nonmolecular solvent anions upon the ionization. Perhaps this is misleading Most polar liquids studied by radiation chemists are aliphatic alcohols and water, and these liquids yield solvated electrons rather than radical ions. Although there has been sporadic interest in other polar liquids (e.g., neat acetone), the current state of knowledge of such systems does not allow one to reach any conclusion as to the nature of the reducing species observed therein (although, see Sec. 4). 

SOLVENT ANIONS AND ELECTRON LOCALIZATION IN LIQUID ACETONITRILE... 

Class (3) reactions include proton-transfer reactions of solvent holes in cyclohexane and methylcyclohexane [71,74,75]. The corresponding rate constants are 10-30% of the fastest class (1) reactions. Class (4) reactions include proton-transfer reactions in trans-decalin and cis-trans decalin mixtures [77]. Proton transfer from the decalin hole to aliphatic alcohol results in the formation of a C-centered decalyl radical. The proton affinity of this radical is comparable to that of a single alcohol molecule. However, it is less than the proton affinity of an alcohol dimer. Consequently, a complex of the radical cation and alcohol monomer is relatively stable toward proton transfer when such a complex encounters a second alcohol molecule, the radical cation rapidly deprotonates. Metastable complexes with natural lifetimes between 24 nsec (2-propanol) and 90 nsec (tert-butanol) were observed in liquid cis- and tra 5-decalins at 25°C [77]. The rate of the complexation is one-half of that for class (1) reactions the overall decay rate is limited by slow proton transfer in the 1 1 complex. The rate constant of unimolecular decay is (5-10) x 10 sec for primary alcohols, bimolecular decay via proton transfer to the alcohol dimer prevails. Only for secondary and ternary alcohols is the equilibrium reached sufficiently slowly that it can be observed at 25 °C on a time scale of > 10 nsec. There is a striking similarity between the formation of alcohol complexes with the solvent holes (in decalins) and solvent anions (in sc CO2). 

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