Ammonia solvated electron

Teledyne Commodore Fluid-jet cutting access and drain agent wash out energetics with ammonia. Solvated electron process in ammonia for reduction chemical oxidation with sodium persulfate. Solvated electron process in ammonia for reduction chemical oxidation with sodium persulfate. Wash in solvated electron solution oxidation to 3X C ship to Rock Island Arsenal for 5X treatment. Crushed or shredded treated in solvated electron solution shipped to landfill. 

In strongly basic solvents like HMPA, amines and liquid ammonia, solvated electrons are relatively stable. In these solvents, if the supporting electrolyte is the salt of Li+ or Na+, blue solvated electrons, esm are generated from the surface of the platinum electrode polarized at a very negative potential ... 

The stability of the solvated electron in the various solvents varies greatly depending on the reactivity of the electron with the solvent. In liquid ammonia solvated electrons are stable for long periods in the blue solutions of alkali metals in ammonla(45). In watjr, eaq decays slowly by reaction (9) with a rate constant of 16 M s (46)... 

Alkali metals dissolve in liquid ammonia at -33°C to produce a deep blue solution containing the metal cation and ammonia-solvated electrons. 

Experimentally, electrons can be injected into and dissolve in molecular liquids. In liquid ammonia solvated electrons form blue, relatively stable, solutions. In water, solvated electrons can be created by photoionizing solute anions or even neat water. These electrons eventually disappear by recombining with the parent species, but live long enough as distinct species with a typical absorption peak near 7000 A. Provided that the injection and subsequent probing are done with ultrafast time resolution, it is possible to follow the solvation process of the electron via its evolving spectrum. 

The ammonia-solvated electron is stable for several hours at — 33°C, and is a powerful reducing agent (Salot and Warf, 1968). 

The formation of carbon-hydrogen bonds from halogen-containing compounds has been carried out by a number of procedures reductive dehalogenation of halogeno-phenol with Raney alloys in alkaline D2O provides a route to deu-teriated phenols treatment of dichlorobenzene with Na or K in liquid ammonia ( solvated electrons ) gives benzene, and, in addition, aniline via benzyne. ... 

Solutions of alkali metals in liquid ammonia are used in organic chemistry as reducing agents. The deep blue solutions effectively contain solvated electrons (p. 126), for example... 

Evidence for the solvated electron e (aq) can be obtained reaction of sodium vapour with ice in the complete absence of air at 273 K gives a blue colour (cf. the reaction of sodium with liquid ammonia, p. 126). Magnesium, zinc and iron react with steam at elevated temperatures to yield hydrogen, and a few metals, in the presence of air, form a surface layer of oxide or hydroxide, for example iron, lead and aluminium. These reactions are more fully considered under the respective metals. Water is not easily oxidised but fluorine and chlorine are both capable of liberating oxygen ... 

Europium and Yb display further similarity with the alkaline earth metals in dissolving in liquid ammonia to give intense blue solutions, characteristic of solvated electrons and presumably also containing [Ln(NH3)x]. The solutions are strongly reducing and decompose on standing with the precipitation of orange Eu(NH2)2 and brown Yb(NH2)2 (always contaminated with Yb(NH2)3) which are isostructural with the Ca and Sr amides. 

Alkali metals in liquid ammonia can transfer an electron to the solvent, leading to so-called solvated electrons. These can add to the aromatic substrate 1 to give a reduced species, the radical anion 3 ... 

Solution of alkali metals in liquid ammonia, containing the so-called solvating electrons, may be used as an alternative homogeneous system to initiate polymerization by an electron transfer process. This system suffers, however, from complications resulting from proton transfer from ammonia leading to the formation of NH2- ions, which in turn initiate further polymerization.4... 

Alkali and alkaline-earth metals have the most negative standard reduction potentials these potentials are (at least in ammonia, amines, and ethers) more negative than that of the solvated-electron electrode. As a result, alkali metals (M) dissolve in these highly purified solvents [9, 12] following reactions (1) and (2) to give the well-known blue solutions of solvated electrons. 

The alkali metals also release their valence electrons when they dissolve in liquid ammonia, but the outcome is different. Instead of reducing the ammonia, the electrons occupy cavities formed by groups of NH3 molecules and give ink-blue metal-ammonia solutions (Fig. 14.14). These solutions of solvated electrons (and cations of the metal) are often used to reduce organic compounds. As the metal concentration is increased, the blue gives way to a metallic bronze, and the solutions begin to conduct electricity like liquid metals. 

This is called the SrnI mechanism," and many other examples are known (see 13-3, 13-4,13-6,13-12). The lUPAC designation is T+Dn+An." Note that the last step of the mechanism produces ArT radical ions, so the process is a chain mechanism (see p. 895)." An electron donor is required to initiate the reaction. In the case above it was solvated electrons from KNH2 in NH3. Evidence was that the addition of potassium metal (a good producer of solvated electrons in ammonia) completely suppressed the cine substitution. Further evidence for the SrnI mechanism was that addition of radical scavengers (which would suppress a free-radical mechanism) led to 8 9 ratios much closer to 1.46 1. Numerous other observations of SrnI mechanisms that were stimulated by solvated electrons and inhibited by radical scavengers have also been recorded." Further evidence for the SrnI mechanism in the case above was that some 1,2,4-trimethylbenzene was found among the products. This could easily be formed by abstraction by Ar- of Ft from the solvent NH3. Besides initiation by solvated electrons," " SrnI reactions have been initiated photochemically," electrochemically," and even thermally." ... 

Events of electron photoemission from a metal into an aqueous solution had first been documented in 1966 by Geoffrey C. Barker and Arthur W. Gardner on the basis of indirect experimental evidence. The formation of solvated electrons in nonaque-ous solutions (e.g., following the dissolution of metallic sodium in liquid ammonia) had long been known, but it was only in the beginning of the 1950s that their existence in aqueous solutions was first thought possible. It is probably for this reason that even nowadays in aqueous solutions we more often find the term solvated than hydrated electrons. 

In solutions neither H+ nor e can exist in a free state they will be donated only if they are accepted within the solution, e.g., by another acceptor, which may be the solvent and thus cause solvation here the mere solvation of electrons is an exceptional case, but may occur, e.g., in liquid ammonia, where according to Kraus82 the strongly reducing alkali metals dissolve while dissociating into cations M+ and solvated electrons e, which, however, are soon converted into NH2" and H2 gas. Further, from the analogy with acid-base reactions and the definition of... 

For highly polar media, the yield of the solvated electron can serve as a lower limit to the ionization yield. This method needs short-time measurement and may work for liquid water and ammonia. Farhataziz et al. (1974) determined the G value—that is, the 100-eV yield—of solvated electrons in liquid NH3 to be about 3.1 at -50 ns. This corresponds to a W value of 32 eV, compared with the gas-phase value of 26.5 eV. The difference may be attributed to neutralization during the intervening time. In liquid water, it has been found that G(eh) increases at short times and has a limiting value of 4.8 (Jonah et al., 1976 Sumiyoshi et al, 1985). This corresponds to W,. = 20.8 eV compared with Wgas = 30 eV (Combecher, 1980). Considering that the yield of eh can only be a lower limit of the ionization yield, suggestions have... 

Solvated electrons were first produced in liquid ammonia when Weyl (1864) dissolved sodium and potassium in it the solution has an intense blue color. Cady (1897) found the solution conducts electricity, attributed by Kraus (1908) to an electron in a solvent atmosphere. Other workers discovered solvated electrons in such polar liquids as methylamine, alcohols, and ethers (Moissan, 1889 Scott et al, 1936). Finally, Freed and Sugarman (1943) showed that in a dilute metal—ammonia solution, the magnetic susceptibility corresponds to one unpaired spin per dissolved metal atom. 

In most cases, the reaction requires external stimulation in which a catalytic amount of electrons is injected into the solution. Solvated electrons in liquid ammonia, sodium amalgam in the same solvent71 light,66-68 electrodes1167 and... 

The model of metal-ammonia solutions that has emerged is based on ionization of the metal atoms to produce metal ions and electrons that are both solvated. The solvated electron is believed to reside in a cavity in ammonia, and thus it may behave as a particle in a three-dimensional box with quantized energy levels. Transitions between the energy levels may give rise to absorption of light and thereby cause the solutions to be colored. The dissolution process can be represented as... 

The blue color is attributed to the solvated electron. The blue solutions react with ketones to form highly colored substances resembling the metal ketyls formed by reaction with the alkali metals. The blue solutions decompose into trialkylamine and hydrocarbon on standing at the boiling point of liquid ammonia. 

The alkali metals in liquid ammonia give deep coloured solutions which have been shown to contain solvated electrons. The unsaturated system takes up an electron to give an anion radical. There is evidence for this species from electron spin resonance studies. It accepts a proton from the solvent to give a radical which is reduced to a carbanion by another sodium atom. Finally the addition of a proton gives the reduced product. This proton is supplied by a protic solvent like enthanol and not from NH3. 

While sodium, potassium and calcium react immediately with water liberating hydrogen, these metals simply dissolve in ammonia without evolving hydrogen. The solutions contain the metal, metal ion and solvated electrons and act as powerful reducing agents. However, in presence of catalysts these metals react with ammonia and evolve hydrogen. 

Solutions of metals in liquid ammonia conduct electricity better than any salt in any liquid and the main current carrier is the solvated electron. This implies that the electron gets free from the parent metal atom sodium and occupy cavities in the liquid. At higher alkali metal concentrations the solutions are copper coloured and have a metallic lustre and all electrical conductivity studies indicate that they are very similar to liquid metals. 

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