Ammonia from crystals

It was decided to study the system tetrakis (trifluorophosphine) nickel- (0) -ammonia (23) in some detail a smooth reaction was observed when the complex, condensed on excess ammonia at liquid air temperature, was allowed to warm up gradually. Precipitation of colorless crystals, identified as ammonium fluoride in almost stoichiometric amount, based on complete ammonolysis of the phosphorus-fluorine bonds, was observed at temperatures as low as —90° to —80°. Removal of the ammonium fluoride by filtration at temperatures not higher than —50°, and subsequent slow evaporation of the ammonia from the filtrate invariably led to a brown-yellow solid, although a colorless, crystalline material was formed initially. The product was decomposed almost instantaneously by water with precipitation of elemental nickel. Analysis of the hydrolyzate obtained in aqueous hydrochloric acid revealed a nickel-phosphorus-nitrogen atom ratio close to 1 4 4, corresponding to an apparently polymeric condensation product. 

The ammonia-radicle theory.—The oldest hypothesis concerning the nature of the ammonia-compounds, and that adopted by A. L. Lavoisier, supposed ammonia to be an independent base or radicle, saturating acids, and forming salts. This theory has been likened to the etherin theory of J. B. A. Dumas and P. F. G. Boullay. The radicle is NHS sal-ammoniac is NH3+HCI etc. The theory makes no attempt to explain the nature of the other classes of ammonia-compounds nor does it explain the relation of ammonia to ordinary bases, which are metallic oxides, nor the differences between the ammoniacal salts from metallic sails of the same acid. Later on, the theory became associated with the mol. compound theory, so that sal ammoniac was represented by F. A. Kekule as an associated complex of ammonia and hydrogen chloride, in which the ammonia remained tervalent. These compounds were considered to be analogous to double salts, and to substances with water of crystallization. This view was supported by the ready dissociation of sal ammoniac by heat—a subject discussed in connection with ammonium chloride (2. 20, 16). H. Rose also emphasized the analogy between compounds of ammonia and of water in various salts as exemplified by the use of the term ammonia of crystallization. 

Hydrates and ammoniates.—Judging from records of salts with water of crystallization and also with ammonia of crystallization, ammonia, in its tendency to unite with other compounds, probably exceeds water. Just as a salt may unite with water to form a hydrate, so can salts combine with ammonia to form ammoniates, or ammines, e.g. oupric and mercurio chlorides form respectively Cuda.2NH3 and HgCl2.2NH3, etc. 

F. Martin gave 174° for the temp, of explosion. According to L. Wohler and W. Krupko, basic cupric azide, cupric oxyazide, CuO.CuNg, is formed as a yellow hydrated substance when water with normal cupric azide in suspension is heated to 70°-80° in a current of air freed from carbon dioxide until the calculated quantity of hydrazoic acid has been evolved. It inflames at 245°. L. M. Dennis and H. Isham obtained cupric amminoazide,Cu(NHg)Ns,by shaking freshly precipitated black cupric hydroxide, while still moist, with an excess of hydrazoic acid and washed the precipitate. A soln. of the precipitate in aq. ammonia deposits crystals of the salt. It explodes when heated or struck. It is insoluble in water, and soluble in dil. acids,... 

If a mixture of a soln. of the trisodium salt with a slight excess over an eq. proportion of ammonium nitrate be evaporated, ammonia escapes, and the acid soln. is neutralized with ammonia from time to time water is also added if necessary to dissolve any crystals. During the cooling of the hot soln., crystals of sodium ammonium nitratoimidodisulphonate, NH(NH4S03)2.NaN03, are formed in small, flat, thick prisms, which are anhydrous, and stable in air. The salt cannot be washed with water, or recrystallized from water without hydrolysis. If too little ammonium nitrate is used the complex salt is contaminated with some disodium imidosulphonate. The constitution is represented with quinquevalent nitrogen ... 

Tris(phenylbiguanido)cobalt(III) hydroxide, [Co(C6-H5C2N6H5) 3]-3H20 or [Co(C6H6C2N6H6) 3] (OH) 3, forms rose-red crystals which melt with decomposition near 200° and are insoluble in water and alcohol. The compound absorbs carbon dioxide from the atmosphere and liberates ammonia from solutions of ammonium salts on boiling. Boiling water and alkali have no action upon the complex base, but concentrated acids decompose it. The anhydrous material may be obtained by heating the hydrate to 145 to 150° for 24 hours, but it readily absorbs water on exposure to air. The substance is preserved in an atmosphere free from carbon dioxide. 

K4[Ni(CN)4] also belongs to this group it is produced from potassium in liquid ammonia from normal K2[Ni(GN)4]. The former can perhaps be regarded as a complex, built up from a nickel atom and four CN ions, thus with 10 + 4 X 2 electrons around the central atom in a krypton configuration, in place of 8 + 4 X 2 as in the ordinary complex of Ni2+. One would have to expect tetrahedral sp3 bonding as opposed to the normal dsp2 bonding in K2[Ni(CN)4] the crystal structure is, however, not known. 

When the first crop has been collected, the liquid is returned to the pan. Then the crystals of product are rinsed off. To do this, they are packed back into the filtering funnel and rinsed off with 190 proof grain alcohol. A few rinses should remove the smell of ammonia from them. Then they should be spread out on fresh wax paper until they are dry. They should have no smell. They should also be clear or white in color. 

The alkaloid or poisonous principle was isolated from the powdered and dried tubers by extraction with 96% ethanol that contained some acetic acid (40). The sirupy residue, after removal of the solvent, was agitated with aqueous sodium carbonate solution and the base extracted with chloroform. Crystallization of the base proved difficult but its purification as hydrobromide by fractional crystallization proved satisfactory. The alkaloid recovered represents 0.21% of the weight of the dried tubers (0.04% of the fresh tubers). It is a low melting solid and is sufficiently basic to liberate ammonia from its salts. 

TPD of ammonia from iron single-crystal surfaces following high-pressure ammonia synthesis proves to be a sensitive probe of the new surface binding sites formed upon restructuring. Ammonia TPD spectra for the four clean surfaces are shown in Figure 7.19. Each surface shows distinct desorption sites. The Fe(llO) surface displays one desorption peak ( 2) with a peak maximum at 658 K. Two desorption peaks are seen for the Fe(lOO) surface 2 1 3) 556 K and 661 K. 

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