Ammonium preparation

Fosamin-ammonium, prepared by the reaction of triethylphosphite, methyl chloroformate and ammonia, is a crystalline compound with a melting point of 175°C, readily soluble in water (at 25 C, 1.79 kg/kg water). It hydrolyses in dilute acid solution (Schwerdtfeger and Allison, 1976). 

Elixir of Bromide of Ammonium. Prepared from bromide of ammonium as in No. 5449, without the coloring. 

Simplest examples are prepared by the cyclic oligomerization of ethylene oxide. They act as complexing agents which solubilize alkali metal ions in non-polar solvents, complex alkaline earth cations, transition metal cations and ammonium cations, e.g. 12—crown —4 is specific for the lithium cation. Used in phase-transfer chemistry. ... 

Ethylamine, monoethylamine, CH3CH2NH2-B.p. 19 C. Prepared by reduction of acetonitrile or by heating ethyl chloride with alcoholic ammonia under pressure. It is a strong base and will displace ammonia from ammonium salts. Forms a crystalline hydrochloride and also crystalline compounds with various metallic chlorides. 

Prepared by heating ammonium mucate, or from butyne-l,4-diol and ammonia in the presence of an alumina catalyst. The pyrrole molecule is aromatic in character. It is not basic and the imino-hydrogen atom can be replaced by potassium. Many pyrrole derivatives occur naturally, e.g. proline, indican, haem and chlorophyll. 

It is prepared by the direct nitration of toluene with a mixture of nitric and sulphuric acids. TNT is a very stable, violent and powerful high explosive, but less sensitive to shock and friction than picric acid. It is widely used as a filling for shells, bombs, etc. often mixed with ammonium nitrate and other high explosives. The lower grades of TNT may contain isomers which under hot storage conditions may give rise to exudation. 

It is best prepared by heating an intimate mixture of solid ammonium chloride and quicklime ... 

Ammonium salts. Ammonium salts can be prepared by the direct neutralisation of acid by ammonia. The salts are similar to alkali metal salts and are composed of discrete ions. Most ammonium salts are soluble in water. Since ammonia is volatile and readily oxidisable the behaviour of ammonium salts to heat is particularly interesting. 

Towards a simple Lewis base, for example the proton, phosphine is a poorer electron donor than ammonia, the larger phosphorus atom being less able to form a stable covalent bond with the acceptor atom or molecule. Phosphine is, therefore, a much weaker base than ammonia and there is no series of phosphonium salts corresponding to the ammonium salts but phosphonium halides. PH4X (X = Cl, Br, I) can be prepared by the direct combination of phosphine with the appropriate hydrogen halide. These compounds are much more easily dissociated than ammonium halides, the most stable being the iodide, but even this dissociates at 333 K PH4I = PH3 -t- HI... 

This can be prepared by the controlled reduction of a nitrite (nitrate(lll)) or nitrate. Cautious heating of ammonium nitrate gives dinitrogen oxide by an internal oxidation-reduction process ... 

Uses of hydrogen chloride—Hydrogen chloride is sometimes used in the preparation of an ester, for example ethyl benzoate, where it acts as both an acid catalyst and a dehydrating agent. Hydrochloric acid is used primarily to produce chlorides, for example ammonium chloride. It is extensively used in the manufacture of anilme dyes, and for cleaning iron before galvanising and tin-plating. 

Tartaric acid is noteworthy for a) the excellent way in which the majority of its salts Crystallise, and h) the frequent occurrence of salts having mixed cations. Examples of the latter are sodium potassium tartrate (or Rochelle salt), C4H40 NaK, used for the preparation of Fehling s solution (p. 525), sodium ammonium tartrate, C4H OaNaNH4, used by Pasteur for his early optical resolution experiments, and potassium antimonyl tartrate (or Tartar Emetic), C4H404K(Sb0). The latter is prepared by boiling a solution of potassium hydrogen tartrate (or cream of tartar ) with antimony trioxide,... 

Urea (the diamide of carbonic acid) can be prepared by the historic method of Wohler. When an aqueous solution of ammonium cyanate is allowed to stand, the cyanate undergoes molecular rearrangement to urea, and an equilibrium mixture containing about 93% of urea is thus formed. Urea is... 

Ammonium cyanate, because of its instability in solution, is usually prepared (NHJaSO, + 2KCNO 2NH4CNO + KjSO by mixing aqueous solutions of ammonium sulphate and potassium cyanate. Complete evaporation then gives a mixture of potassium sulphate and urea, from which the urea may be extracted w ith hot absolute ethanol, in which potassium sulphate is insoluble. 

When the potassium cyanate used in the above preparation is replaced by potassium thiocyanate (or sulphocyanide), the ammonium thiocyanate formed undergoes partial rearrangement to thiourea (or sulpho-urea). Even above... 

Mono-substituted and unsymmetrical di-substituted ureas may be prepared by a modification of Wohler s urea synthesis, salts of primary or secondary amines being used instead of the ammonium salt for interaction with potassium cyanate. Thus when an aqueous solution containing both aniline hydrochloride and potassium cyanate is heated, aniline cyanate is first formed, and then C,HjNH,HCl -h KCNO = C,H6NHj,HCNO -h KCl C,HsNH HCNO = C.H NHCONH, by the usual molecular rearrangement is converted into monophenyburea. 

The ammonium cyanate then reacts with the aniline hydrochloride giving aniline cyanate which, as in the previous preparation, gives in turn monophenylurea. 

The above method of preparing a neutral solution of the ammonium salt cannot be applied to extremely weak acids (e.g., some amino-acids), the ammonium salts of which dissociate in boiling aqueous solution. 

This preparation illustrates the preparation of a liquid hydrocarbon from a Grignard reagent. The Grignard reagent from n-hexyl bromide may be decomposed either with dilute sulphuric acid or with solid ammonium chloride the latter gives a somewhat better 3neld. 

The method is generally applicable when other modes of esterification are either slow, inefficient, or likely to cause isomerisation it is, however, time-consuming and expensive. Small quantities of acid impurities are sometimes produced, hence it is advisable to wash the ester with saturated sodium bicarbonate solution. The silver salt can usually be prepared by dissolving the acid in the calculated quantity of standard ammonium hydroxide solution and... 

An excess of acetic acid is usually added before heating in order to repress the hydrolysis (and also the thermal dissociation) of the ammonium acetate, thus preventing the escape of ammonia. The excess of acetic acid, together with the water, is removed by slow fractional distillation. The method is rarely used except for the preparation of acetamide. 

Amino acids may be prepared by the action of a large excess of concentrated ammonia solution upon a-chloro- or a-bromo-acids the presence of a considerable amount of ammonium carbonate often increases the yield of monoamino acid, for example ... 

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