Solutions in ammonia

Tyrosine and cystine are colourless solids almost insoluble in water gfid in ethanol (tyrosine dissolves in hot water). They are readily soluble in dilute caustic alkali solution, in ammonia and mineral acids, but not in acetic acid. They are also classed as neutral ampholytes. ... 

In recent years, trimethylsilyl protection has often been used for the methine proton of the acetylenic group because of the mild reaction conditions for desilylation. As a rule, the starting pyrazole trimethylsilyl derivative is mixed up, at room temperature, with a 2 A aqueous solution of NaOH, potash, or methanol solution in ammonia. 

Hydrazine and its Derivatives, Schmidt, F. W., New York, Wiley, 1984, 75 Use of excess calcium metal, or its solution in ammonia (presumable calcamide) to dry hydrazine leads to formation of calcium hydrazide and explosion. Calcium hydride and carbide are, apparently, safe drying agents... 

A white powder, or small, lustrous, colorless needles (when crystallized from hot water), which carbonize but do not melt on being heated. Naphthylaminesulphonic acid is soluble in about 4000 parts of cold water, more readily in hot water, scarcely soluble in alcohol, and insoluble in ether. The solution in ammonia water exhibits a violet fluorescence. 

Silver orthoarsenate dissolves in hydrochloric acid, forming arsenic trichloride,11 and in nitric acid with partial conversion to nitrato-arsenate,12 which may be separated by fractional crystallisation, silver orthoarsenate crystallising out first and then the nitrato-arsenate the latter, in contact with water, reverts to silver nitrate and silver orthoarsenate. The latter is also soluble in acetic acid, and in aqueous ammonia or ammonium carbonate. By crystallising the solution in ammonia over a mixture of quicklime and sal-ammoniac, colourless needles of silver tetrammino-orthoarsenate, Ag3As04.4NTI3, are obtained 13 these lose ammonia in the air and turn reddish-brown. 

In applying these ideas to metal solutions in ammonia, the restrictions on the Thomas-Fermi screening approach have generally been ignored. At metallic concentrations the concentration of free ammonia molecules is low, and the dielectric constant is near unity the pure ammonia value of Ke is only applicable when solvent molecules are not polarized by the ions. If we choose m /m less than unity, then fitting the theory to experimental data on conductivity becomes impossible. For the calculated conductivity to agree with the measured conductivity, we require... 

Figure 3. The Hall coefficient of lithium, sodium, and calcium solutions in ammonia.

A in aft) provided aft is obtained directly from experimental parameters that characterize the localized electron state. The data (64, 68, 69) for metal solutions in ammonia, methylamine, and HMPA are included in Fig. 22. Inherent in the Mott picture (124) is a major change in the thermodynamic properties of the solutions in the transition region. This important feature is discussed in Section IV,B. 

Similar properties to the much more widely investigated sodium amide, but may be expected on general grounds to be more violently reactive. The frequent fires or explosions observed during work-up of reaction mixtures involving the amide were attributed to presence of unreacted (oxide-coated) particles of potassium in the amide solution in ammonia. A safe filtration technique is described.2... 

Potassium benzenetellurolate is stable for months under an atmosphere of nitrogen, but decomposes readily in contact with oxygen or moisture. The tellurolate is soluble in liquid ammonia, in acetone, and in tetrahydrofuran. The color of the solution in ammonia is orange1. 

In 1864, W Weyl also observed the blue color of alkali metals solutions in ammonia, methylamine and ethyl amine and found that the resulting solutions had reducing properties, when used in chain synthesis. However, W Weyl did not discover the nature of these blue solutions. Nowadays, it is known that the blue color is due to the solvated electron, as alkali metals dissolved in amine solvents give the metal cation and a solvated electron as in the case of sodium ... 

From the first observations of the blue color of alkali metal solutions in ammonia, the major characteristic of the solvated electron is its optical properties. 

Silver chromate is almost insoluble in water, glacial acetic acid, and in solutions of potassium chromate, but soluble in those of ammonia, caustic alkalies, nitrates, and in dilute acetic acid. A concentrated solution of ammonium nitrate is a good crystallising medium for silver chromate. With chlorine, above 200° C., silver chloride, chromium trioxide, and oxygen are produced. The solution in ammonia contains the compound Ag2Cr04.4NH3, which forms crystals isomorphous with the corresponding ammoniacal sulphate. ... 

Ammonia (b.p. —33, e 22) is, like water, an unsymmetrical molecule with a lone pair and a fairly high dipole moment. The autoprotolysis reaction is slight [NH4+][NH2 ] IO-22 at the boiling point (—33°). The protonic acid, NH4+, from ammonium salts in solution in ammonia, liberates hydrogen with such metals as calcium ... 

Cyelodehydration. The first recorded use of the reagent provides a dramatic comparison in potency of PPA with three other reagents. In the synthesis of dibenz-coronene and coronene, Scholl and Meyer effected the first of four ring closures of the hexacarboxylic acid (I) with concentrated sulfuric acid at room temperature. The red-violet product (2) was obtained in analytically pure form by precipitation from a solution in ammonia. C ycli/.alion to (.1) was accomplished with 20% oleum at 100° the product was isolated us the violet-black sodium salt by adding sodium... 

The simplest approach to avoid thc distillation and to separate the polyynes from PAHs and carbon is to precipitate them as copper salts, taking advantage of a particular property of the hydrogen-terminated acetylenes to react with Cu(I) salt solutions to produce acetylides. Thus, the polyyne acetylides precipitate as brown powders by stirring a concentrated solution of these molecules in decalin with a Cu(I) solution in ammonia. The filtration permits the recovery of these molecules as the copper salts. 

When compared with the corresponding solutions in ammonia, solutions of lithium in amines appear as stronger but less selective reducing agents. 

The metal amides are the outstanding bases in the ammonia system with which acid (XXVIII) can be neutralized. In order to convert this acid (XXVIII) into a salt, Berg and Goehring (19) reacted its solutions in ammonia with KNH2. A yellow solid with the composition K3N3S2 was pro-... 

The determination of chloride involves the precipitation of chloride with silver nitrate, dissolution of the precipitate in ammonia, and determination of silver in the resulting solution by FAAS using air-acetylene or air-hydrogen flames. Standard silver nitrate solutions in ammonia are used for calibration since bromide and iodide interfere in the determination of chloride. 

Formula 28 is the striker or friction formula for the commercial safety match. Nowadays, the binder is always insolubilized either by a special hardening process,a formaldehyde treatment, or use of a casein solution in ammonia. This prevents the staining formerly experienced when matchbooks were carried in shirt pockets and subjected to perspiration or exposed to rain, The striking strip can also be made with hydrophobic binders such as nitrocellulose or various plastic emulsions, but the quality of such a very moisture-resistant striker is generally inferior as are all special formulas designed to make the striking strip adhere well to foil, plastic, metal, or other impervious surfaces. 

This result was confirmed with other substances and showed in evidence that unstable free radicals by irradiation generated at liquid nitrogen temperature could be preserved and stabilized at room temperature by freeze-drying of their solution in ammonia at very low temperatures. This, of course, would be strictly impossible in a water solution. 

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