Ammonia, aqueous

Prepared by heating p-nitrochlorobenzene with concentrated aqueous ammonia in an autoclave at 170°C. It is also prepared by alkaline hydrolysis of p-nitroacetanilide or by nitrating and hydrolysing benzylideneaniline. 

Aqueous ammonia can also behave as a weak base giving hydroxide ions in solution. However, addition of aqueous ammonia to a solution of a cation which normally forms an insoluble hydroxide may not always precipitate the latter, because (a) the ammonia may form a complex ammine with the cation and (b) because the concentration of hydroxide ions available in aqueous ammonia may be insufficient to exceed the solubility product of the cation hydroxide. Effects (a) and (b) may operate simultaneously. The hydroxyl ion concentration of aqueous ammonia can be further reduced by the addition of ammonium chloride hence this mixture can be used to precipitate the hydroxides of, for example, aluminium and chrom-ium(III) but not nickel(II) or cobalt(II). 

When chlorine is passed into aqueous ammonia, ammonium chloride and nitrogen are formed. If, however, sodium chloratefi) (hypochlorite) is used instead of chlorine, chloramine is first formed ... 

It is readily dehydrated on warming, to give the black oxide CuO. It dissolves in excess of concentrated alkali to form blue hydroxo-cuprate(II) ions, of variable composition it is therefore slightly amphoteric. If aqueous ammonia is used to precipitate the hydroxide, the latter dissolves in excess ammonia to give the deep blue ammino complexes, for example [Cu(NH3)4(H20)2] ... 

The complexes of copper(I) like those of silver(I) (p. 430), but unlike those of preceding transitions metals, tend to prefer a linear coordination of two ligands, i.e. X—Cu—X thus copper(I) chloride in aqueous ammonia gives the colourless [Cu(NH3)2] (readily oxidised in air to give blue [Cu (NH3)4(H20)2] copper(I) chloride in hydrochloric acid gives [CuClj], although [CuCl3] is also known. 

The product, commonly called calomel, is a white solid, insoluble in water in its reactions (as expected) it shows a tendency to produce mercury(II) and mercury. Thus under the action of light, the substance darkens because mercury is formed addition of aqueous ammonia produces the substance HjN—Hg—Hg—Cl, but this also darkens on standing, giving HjN—Hg—Cl and a black deposit of mercury. 

D) Mixed solvent. Add 10 ml. of concentrated aqueous ammonia (t/, o-88o) to 40 ml. of redistilled n-butanol and thoroughly mix to obtain a complete solution. 

Method (1) is most frequently used for aliphatic acid amides, while Methods (2a), (2b) and (zc) are used most frequently for aromatic acid amides. Of the last three methods, the Acid Chloride Method (zb) is the most rapid and certain. The Ester Method (za) is practicable only when the amide is insoluble in water, and even then is often very slow unless the ester itself is appreciabb soluble in the aqueous ammonia solution. 

Succinamide. NHoCOCH2 CH2CONH2. (Method 2(a)). Add 5 ml. (5 8 g.) of dimethyl succinate to a mixture of 50 ml. of water and 25 ml. of concentrated [dy o-88o) aqueous ammonia solution in a 150 ml. conical flask. Cork the flask and shake the contents the dimethyl succinate rapidly dissolves to give a clear solution. Allow the solution to stand after about i hour the succinamide starts to crystallise, and then continues to separate for some time. Next day, filter off the succinamide at the pump, wash with cold water, and drain. Recrystallise from water, from which the succinamide separates as colourless crystals the latter soften at 240° and melt at 254 -255° with... 

Add 15 g, of chloroacetic acid to 300 ml. of aqueous ammonia solution d, o-88o) contained in a 750 ml. conical flask. (The manipulation of the concentrated ammonia should preferably be carried out in a fume-cupboard, and great care taken to avoid ammonia fumes.) Cork the flask loosely and set aside overnight at room temperature. Now concentrate the solution to about 30 ml. by distillation under reduced pressure. For this purpose, place the solution in a suitable distilling-flask with some fragments of unglazed porcelain, fit a capillary tube to the neck of the flask, and connect the flask through a water-condenser and receiver to a water-pump then heat the flask carefully on a water-bath. Make the concentrated solution up to 40 ml. by the addition of water, filter, and then add 250 ml. of methanol. Cool the solution in ice-water, stir well, and set aside for ca. I hour, when the precipitation of the glycine will be complete. 

Toluene p ulphonyl chloride reacts with aqueous ammonia to give the... 

Action of ammonia. To i ml. of aldehyde add i ml. of aqueous ammonia a precipitate of hydrosalicylamide, (HOC,H4CH)3N2, is rapidly produced. 

Preparation of silver maleate. Dissolve 65 g. of pure maleic acid (Section 111,143) in the calculated quantity of carefully standardised 3-5N aqueous ammonia solution in a 1-htre beaker and add, whilst stirring mechanically, a solution of 204 g. of silver nitrate in 200 ml. of water. Filter oflf the precipitated silver maleate at the pump, wash it with distilled water, and press well with the back of a large flat glass stopper. Dry in an electric oven at 50-60° to constant weight. The yield of the dry silver salt is 150 g. Store in a vacuum desiccator in the dark. 

By the action of concentrate aqueous ammonia solution upon esters. This process is spoken of as ammonolysls of the ester, by analogy with hydrolysis applied to a similar reaction with water. If the amide is soluble in water, e.g., acetamide, it may be isolated by distillation, for example ... 

Gyanoacetamide. Place 150 ml. of concentrated aqueous ammonia solution (sp. gr. 0-88) in a 500 ml. wide-mouthed conical flask and add 200 g. (188 ml.) of ethyl cyanoacetate. Shake the cloudy mixture some heat is evolved and it becomes clear in about 3 minutes. Stand the loosely stoppered flask in an ice-salt mixture for 1 hour, filter rapidly with suction, and ash the solid with two 25 ml. portions of ice-cold ethanol. Dry in the air the yield of pale yellow cyanoacetamide is 110 g. (1). Recrystallise from 190 ml. of 95 per cent, ethanol a colourless product, m.p. 119-120 , is deposited with practically no loss. 

Pheiiyl iso-thiocyanate may be prepared in quantity directly from aniline. Aniline, carbon disulphide and concentrated aqueous ammonia react to form the sparingly soluble ammonium phenyldithiocarbamate this is decomposed by lead nitrate to produce phenyl iso-thiocyanate ... 

Stir a mixture of 2-4 g. of powdered hydrazine sulphate, 18 ml. of water and 2-4 ml. of concentrated aqueous ammonia (sp. gr. 0-88), and add 4-6 g. (4 4 ml.) of benzaldehyde (free from benzoic acid) dropwise, with stirring, over a period of 30-60 minutes. Stir the mixture for a further hour, collect the solid by suction filtration and wash it with water. RecrystalUse from 8 ml. of rectified spirit. The 3 ield of benzalazine (yellow needles), m.p. 92-93°, is 3-6 g. 

Nicotinamide. Place 50 g. of pure ethyl nicotinate (Section V,23) in a 350 ml. bolt-head flask and add 75 ml. of concentrated aqueous ammonia saturated at 0°. Keep the flask loosely stoppered for 18 hours, after w)iich time the lower layer generally dissolves on shaking. Saturate the solution with ammonia and allow it to stand for a further 4 hours. Repeat the saturation with ammonia crystals of the amide commence to appear in the solution. Evaporate to drjmess in a dish on the steam bath and dry at 120°. The yield of nicotinamide, m.p. 130°, is usuallj quantitative. 

Great caro must be exercised in handling ethyl bromoacetate. Keep a 10 per cent, aqueous ammonia solution available to react with any bromoester which may be spilled. 

The conversion of a diazo ketone to an acid amide may be accomplished by treating a warm solution in dioxan with 10-28 per cent, aqueous ammonia solution containing a small amount of silver nitrate solution, after which the mixture is heated at 60°-70° for some time. Precautions should be taken (by use of a. safety glass shield) when heating mixtures containing ammoniacal silver nitrate. 

Alternatively, treat a solution of 3 9 g. of the 6is-diazo ketone in 50 ml. of warm dioxan with 15 ml. of 20 per cent, aqueous ammonia and 3 ml. of 10 per cent, aqueous silver nitrate under reflux in a 250 or 500 ml. flask on a water bath. Nitrogen is gently evolved for a few minutes, followed by a violent reaction and the production of a dark brown and opaque mixture. Continue the heating for 30 minutes on the water bath and filter hot the diamide of decane-1 lO dicarboxyhc acid is deposited on cooling. Filter this off and dry the yield is 3 -1 g., m.p. 182-184°, raised to 184-185° after recrystallisation from 25 per cent, aqueous acetic add. Hydrolyse the diamide (1 mol) by refluxing for 2-5 hours with 3N potassium hydroxide (4 mols) acidify and recrystaUise the acid from 20 per cent, acetic acid. The yield of decane-1 10-dicarboxyhc acid, m.p. 127-128°, is almost quantitative. 

Nitrogen and sulphur absent, (i) If only one halogen is present, acidify with dilute nitric acid and add excess of silver nitrate solution. A precipitate indicates the presence of a halogen. Decant the mother liquor and treat the precipitate with dilute aqueous ammonia solution If the precipitate is white and readily soluble in the ammonia solution, chlorine is present if it is pale yellow and difficultly soluble, bromine is present if it is yellow and insoluble, then iodine is indicated. Iodine and bromine should be confirmed by the tests given below. 

To a solution of 0.30 mol of ethyllithium (note 1) in about 270 ml of diethyl ether (see Chapter II, Exp. 1) v/as added 0.30 mol of methoxyallene at -20°C (see Chapter IV, Exp. 4) at a rate such that the temperature could be kept between -15 and -2Q°C. Fifteen minutes later a mixture of 0.27 mol of >z-butyl bromide and 100 ml of pure, dry HMPT ivas added in 5 min with efficient cooling, so that the temperature of the reaction mixture remained below 0°C. The cooling bath was then removed and the temperature was allowed to rise. After 4 h the brown reaction mixture was poured into 200 ml of ice-water. The aqueous layer was extracted twice with diethyl ether. The combined solutions were washed with concentrated ammonium chloride solution (which had been made slightly alkaline by addition of a few millilitres of aqueous ammonia, note 2) and dried over potassium carbonate. After addition of a small amount (2-5 ml) of... 

A solution of a-lithiomethoxyallene was prepared from nethoxyal lene and 0.20 mol of ethyllithiurn (note 1) in about 200 ml of diethyl ether (see Chapter II, Exp. 15). The solution was cooled to -50°C and 0.20 mol of ethylene oxide was added immediately. The cooling bath was removed temporarily and the temperature was allowed to rise to -15 c and was kept at this level for 2.5 h. The mixture was then poured into 200 ml of saturated ammonium chloride solution, to which a few millilitres of aqueous ammonia had been added (note 2). After shaking the layers were separated. The aqueous layer was extracted six times with small portions of diethyl ether. The combined ethereal solutions were dried over sodium sulfate and subsequently concentrated in a water-pump vacuum. Distillation of the... 

Exp. 4) in 10 min with cooling at -30°C. After an additional 15 min 0.30 mol of a-chlororaethyl ethyl ether (note 2) was introduced in 10 min, while keeping the temperature between -20 and -30°C. A white precipitate of lithium chloride was formed. The cooling bath was then removed and the temperature was allowed to rise to +10°C. The mixture was hydrolyzed by shaking it with 200 ml of a solution of 30 g of ammonium chloride, to which 5 ml of aqueous ammonia had been added. 

A solution of 0.10 mol of lithiated methoxyallene in about 70 ml of hexane and 50 ml of THF (see Chapter II, Exp. 15) was cooled to -40°C. Ory, pure acetone (0.12 mol) was added dropwise during 10 min, while keeping the temperature at about -30°. Five minutes after the addition 100 ml of saturated NHi,Cl solution, to which 5 ml of aqueous ammonia had been added (note 1), were run in with vigorous stirring. The product was extracted three times with diethyl ether. The combined organic solutions were dried over potassium carbonate and subsequently... 

Direct addition of ammonia to olefmic bonds would be an attractive method for amine synthesis, if it could be carried out smoothly. Like water, ammonia reacts with butadiene only under particular reaction conditions. Almost no reaction takes place with pure ammonia in organic solvents. The presence of water accelerates the reaction considerably. The reaction of aqueous ammonia (28%) with butadiene in MeCN in the presence orPd(OAc)i and PhjP at 80 C for 10 h gives tri-2,7-octadienylamine (47) as the main product, accompanied by a small amount of di-2,7-octadienylamine (46)[46,47], Isomeric branched... 

A standard method for the preparation of an a ammo acid uses a bromo carboxylic acids as the substrate and aqueous ammonia as the nucleophile... 

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