Aluminium Ammonium compounds

The system ammonium nitrate, aluminium, nitro compound (e.g. TNT) would be expected to undergo gradual decomposition, e.g. that in stored shells and bombs filled with such mixtures changes would occur, leading to the oxidation of the aluminium. Obviously, a mixture containing oxidized aluminium has lower explosive power than the same mixture containing metallic aluminium. It was therefore very important to determine the mechanism of the oxidation of aluminium. It became apparent that this is caused by impurities in the ammonium nitrate, not by the... 

Basic groups giving an anion exchange resin can be inserted by first combining with chloromethylether, in the presence of a catalyst such as aluminium chloride. The product, when treated with trimethylamine, yields a quaternary ammonium compound with basic properties such as shown below ... 

I Aluminium compounds I Ammonium compounds [soron compounds Other ... 

In basic inorganic chemical analysis, the cations that students may be required to identify are aluminium, ammonium, calcium, copper(II), iron(II), iron(III), lead(II) and zinc. The reagents used are usually sodium hydroxide and ammonia solutions. Whether a precipitate (an insoluble hydroxide) is formed, the colour of the precipitate and further reaction, if any, of the precipitate with excess sodium hydroxide and/or ammonia solution, aU give clues to the identity of the cations present. The liberation of ammonia when sodium hydroxide solution is added to an unknown compound and gendy heated indicates the presence of the ammonium ion. Flame tests are also used to identify certain cations, for example, sodium, potassium and copper(II), as they give distinctive coloured flames when heated in a non-luminous flame. 

The precipitate is soluble in free mineral acids (even as little as is liberated by reaction in neutral solution), in solutions containing more than 50 per cent of ethanol by volume, in hot water (0.6 mg per 100 mL), and in concentrated ammoniacal solutions of cobalt salts, but is insoluble in dilute ammonia solution, in solutions of ammonium salts, and in dilute acetic (ethanoic) acid-sodium acetate solutions. Large amounts of aqueous ammonia and of cobalt, zinc, or copper retard the precipitation extra reagent must be added, for these elements consume dimethylglyoxime to form various soluble compounds. Better results are obtained in the presence of cobalt, manganese, or zinc by adding sodium or ammonium acetate to precipitate the complex iron(III), aluminium, and chromium(III) must, however, be absent. 

Ammonium perchlorate has, in addition to the properties mentioned for the previous compounds, a specific instability due to its unfavourable oxygen balance. Friction is enough to make it detonate. Combined with aluminium it has been used as a propellant for rockets. In the presence of carbon and metal salts, it reacts exothermically below 240°C and detonates above this temperature. 

Many of the following powdered metals reacted violently or explosively with fused ammonium nitrate below 200°C aluminium, antimony, bismuth, cadmium, chromium, cobalt, copper, iron, lead, magnesium, manganese, nickel, tin, zinc also brass and stainless steel. Mixtures with aluminium powder are used as the commercial explosive Ammonal. Sodium reacts to form the yellow explosive compound sodium hyponitrite, and presence of potassium sensitises the nitrate to shock [1], Shock-sensitivity of mixtures of ammonium nitrate and powdered metals decreases in the order titanium, tin, aluminium, magnesium, zinc, lead, iron, antimony, copper [2], Contact between molten aluminium and the salt is violently explosive, apparently there is a considerable risk of this happening in scrap remelting [3],... 

Solid lithium aluminium hydride can be solublized in non-polar organic solvents with benzyltriethylammonium chloride. Initially, the catalytic effect of the lithium cation in the reduction of carbonyl compounds was emphasized [l-3], but this has since been refuted. A more recent evaluation of the use of quaternary ammonium aluminium hydrides shows that the purity of the lithium aluminium hydride and the dryness of the solvent are critical, but it has also been noted that trace amounts of water in the solid liquid system are beneficial to the reaction [4]. The quaternary ammonium aluminium hydrides have greater hydrolytic stability than the lithium salt the tetramethylammonium aluminium hydride is hydrolysed slowly in dilute aqueous acid and more lipophilic ammonium salts are more stable [4, 5]. 

Military propellants are based on relatively powerful oxidisers and fuels of high calorihc value in order to develop an improved thrust or impulse. Thus the most commonly-used oxidisers are potassium perchlorate, ammonium perchlorate or more esoteric compounds such as hydrazinium nitroformate. Metallic fuels include aluminium, magnesium and beryllium, while binders are mainly hydrocarbons such as polybutadiene, polyisobutylene, polyurethane or poly(vinyl chloride) (PVC) as presented in Table 3.2. 

All the compounds formed decompose immediately in water with formation of aluminium hydroxide. The most stable derivative is the hexammine gaseous hydrogen chloride at —15° C. has little action upon it, at 0° C. the compound is attacked slowly, and at 15° C. it is rapidly converted into ammonium chloride and aluminium chloride. 

It is well known that ammonium nitrate evolves ammonia on storage, particularly in the presence of moisture. It was found that the amount of ammonia evolved in the presence of aluminium is much greater [63]. The evolution of ammonia is particularly undesirable in the mixtures containing TNT, as TNT reacts with ammonia to yield readily ignitable compounds (Vol. I, p. 304 see also [64]). 

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