Liberation of ammonia

Discussion. When a solution of an orthophosphate is treated with a large excess of ammonium molybdate solution in the presence of nitric acid at a temperature of 20-45 °C, a precipitate is obtained, which after washing is converted into ammonium molybdophosphate with the composition (NH4)3[P04,12Mo03]. This may be titrated with standard sodium hydroxide solution using phenolph-thalein as indicator, but the end point is rather poor due to the liberation of ammonia. If, however, the ammonium molybdate is replaced by a reagent containing sodium molybdate and quinoline, then quinoline molybdophosphate is precipitated which can be isolated and titrated with standard sodium hydroxide ... 

Glutamate dehydrogenase, the enzyme responsible for the liberation of ammonia from amino acids, occurs in two forms one (cytosolic) is nicotinamide adenine dinucleotide (NAD+) dependent whilst the other (mitochondrial) requires NADP+ as coenzyme. 

Reaction with sodium amide also yields the same compound with liberation of ammonia ... 

HMTD is destroyed by caustic soln with liberation of ammonia (Ref 16). It can be nitrated at low temps using HN03 to give ca 26% RDX (Ref 18)... 

Although beryllium and magnesium salts do not form stable mctal-ammines yet they unite with ammonia, forming additive compounds of the hydrate type which are sometimes referred to as ammoniates or ammonio-compounds. These appear to be of the same type as the metal-anunines, and the difference seems to be merely one of stability. The ammonio-compounds are formed by the addition of ammonia gas to dry or fused salt, and most of them decompose with liberation of ammonia when dissolved in water. 

The halides of strontium resemble those of calcium, and unite with ammonia gas in the dry state. All are decomposed by water with liberation of ammonia. The chloride, on exposure to ammonia gas, yields octammino-strontium chloride, [Sr(NII3)8]Cl2. It is a voluminous white powder which loses ammonia on heating, leaving a residue of strontium chloride. If degraded isothermally, constancy of pressure indicates the existence of monammino-strontium chloride, [Sr(NH3)]Cl2, which on further heating loses ammonia completely. The monammine at a temperature of 45-5° C. has a dissociation pressure of 100 mm.4... 

The amide is a greyish-white powder which is stable below 0° C. out of contact with air, and decomposes in water with liberation of ammonia. If heated above 0° C. the amide decomposes slowly into the imide, As2(NH)3, decomposition being complete at 60° C. The reaction may be expressed by the equation... 

Wright and McKay [49] suggest a different reaction mechanism for the N-methyl-N -nitroguanidine in the first stage it involves the addition of methylamine to the nitroimine form of nitroguanidine, and this is followed by the liberation of ammonia and the formation of methylnitroguanidine (I). 

Ammonium Salts. — On boiling 1 gm. of molybdic anhydride with sodium hydroxide solution, there must be no liberation of ammonia (to be ascertained by means of moistened litmus paper). 

The trichloride dissolves in liquid cyanogen.1 It combines with cyanogen bromide when a mixture of the two is slowly heated in an autoclave to 180° C., followed by cooling and keeping at 120° C. for one hour 2 the product, of composition AsCls.2BrCN, decomposes on heating above 190° C. Arsenic trichloride reacts with potassium thiocyanate solution,3 the latter being decomposed with liberation of ammonia, but no precipitate is produced, whereas both tin and antimony are precipitated as hydroxides under similar conditions the reaction with excess of potassium thiocyanate may be used to effect a quantitative separation of these two metals from arsenic. 

The existence of two separate enzymes in animal tissues responsible for the liberation of ammonia from each of the two aminopurines, adenine and guanine, the latter specific for the free purine and the former for the nucleosides, was initially presented by Jones and his colleagues 11, 12). In 1928, Schmidt 13-15) demonstrated that AMP aminohy-drolase was responsible for the appearance of inosinic acid in muscle and for at least a portion of ammonia liberated during contraction. He showed not only a marked specificity for deamination of 5 -AMP but also provided the first clue that muscle adenylic acid (5 -AMP) and yeast adenylic acid (3 -AMP) were different compounds. Initial evidence for guanine and adenosine aminohydrolase including aspects of the specificity were also described by Schmidt 16). Additional details regarding development of interest in purine aminohydrolases are available in several excellent reviews 17-20). 

TAGN can be prepd by reacting one mole of guanidine dinitrate with three moles of hydrazine hydrate at 100° for four hrs. The reaction is accompanied by the liberation of ammonia (Ref 18). It can also be prepd by the aq fusion of hydrazine nitrate and Ca cyanamide (Ref 4)... 

Liberation of ammonia and other amines by irradiating amino acids has been reported (7, 15, 17), and a slight increase in ammonia is seen in Table IV at high levels of irradiation, whether by 7-ray or electron beam. 

Five grams (0.0135 mol) of tris(biguanido) chromium (III) 1-hydrate is dissolved in 200 ml. of water and treated with a solution of 5,7 g. (0.043 mol) of ammonium sulfate in 10 ml. of water. The sparingly soluble tris(biguanide)-chromium sulfate is precipitated with liberation of ammonia. The mixture is heated on the water bath, whereby... 

Chloropentaamminecobalt(III) chloride forms red-violet rhomb-shaped crystals which decompose on heating above 150° with the stepwise loss of ammonia. The solubility of the salt in water at 25° is 0.4 g./lOO ml. The compound readily aquates in hot water, forming the aquopentaammine chloride. Chloropentaamminecobalt(III) chloride reacts with hot aqueous ethylenediamine or dZ-propylenediamine to form tris (ethylenediamine) cobalt (III) chloride or the corresponding propylenediamine compound, with liberation of ammonia. Concentrated sulfuric acid at room temperature produces a complex hydrogen sulfate of the chloro-pentaamminecobalt(III) ion. Aqueous mercury(II) chloride forms a characteristic precipitate of a double salt, [Co(NH3)6Cl]Cl2-3HgCl2, suitable for microchemical identification. Complete physical and chemical data may be found in Gmelin s handbook. ... 

It has been found that when molybdenum oxide, hydroxide, or a mixture of either of these compounds Yith the metal, is heated at 500° to 600° C. with equal parts of nitrogen and hydrogen under a pressure of 60 atmospheres, there is formed a nitride of molybdenum. The same compound may be obtained under atmospheric pressure by reducing pure precipitated moiybdic acid by means of hydrogen at 700° C., and then passing nitrogen over the product at the same temperature. The commercial importance of this substance lies in the fact that on heating in a vacuum it yields pure metallic molybdenum, wdth simultaneous liberation of ammonia. 

The nitrides have high melting points, ranging from 2200°C (Be3N2) to 900°C (Ca3N2) and are hydrolysed by water to the hydroxides with liberation of ammonia. 

---