Silver nitrate ammoniacal

Note cautiously the characteristic odour of acetaldehyde which this solution possesses. Then with the solution carry out the following general tests for aldehydes described on p. 341 Test No. I (SchiflF s reagent). No. 3 (Action of sodium hydroxide). No. 4 (Reduction of ammoniacal silver nitrate). Finally perform the two special tests for acetaldehyde given on p. 344 (Nitroprusside test and the Iodoform reaction). 

Give silver mirror with ammoniacal silver nitrate. 

Reduction of ammoniacal silver nitrate. Place about 5 ml. of AgNOj solution in a thoroughly clean test-tube, and add 2-3 drops of dil. NaOH solution. Add dil. ammonia solution, drop by drop, until the precipitated silver oxide is almost redissolved, then add 2 - 3 drops of formaldehyde or acetaldehyde. A silver mirror is formed. 

Reduction of ammoniacal silver nitrate. Add a few drops of a neutral solution of a formate to ammoniacal AgNO (see Test 4, p. 342). A silver mirror or more usually a grey precipitate of metallic sih er is produced on boiling. 

Reduction of ammoniacal silver nitrate. Add i drop of dil. NaOH solution to about 5 ml. of AgNO, solution, and add dil. NH solution drop by drop until the silver oxide is almost redissolved. Add AgNO, solution until a faint but permanent precipitate is obtained (see p.525). Then add 0 5 ml. of a neutral tartrate solution. Place the tube in warm water a silver mirror is formed in a few minutes. 

Reduction of ammoniacal silver nitrate. Place 2 ml. of dilute silver nitrate solution in a clean test-tube. Add 1 drop of NaOH solution and then add dil. ammonia drop by drop until the precipitate formed by the NaOH is just not redissolved. Now add 1-2 ml. of glucose solution and place the test-tube in a water-bath at 50-60° a silver mirror is produced in 1 - 2 minutes. 

Does not reduce ammoniacal silver nitrate or Fehling s solution. If, however, the sucrose solution is warmed for some time with the reagent in question, slight hydrolysis to glucose and fructose does take place and reduction then occurs occasionally samples of sucrose will rapidly give a silver mirror, presumably owing to impurities. 

Reduces ammoniacal silver nitrate, and Fehling s solution. 

Does not reduce ammoniacal silver nitrate or Fehling s solution, and does not form an osazone. 

Oxidation, (a) Ammoniacal silver nitrate. To a few ml. of ammoniacal AgNOj (preparation, p. 525), add a few drops of cold aqueous benzo quinone solution a silver mirror or (more generally) a dark precipitate of metallic silver is formed in the cold. 

Treat with ammoniacal silver nitrate solution and warm. 

Formation of silver mirror or precipitate of silver indicates reducing agent. (This is often a more sensitive test than I (a) above, and some compounds reduce ammoniacal silver nitrate but are without effect on Fehling s solution.) Given by aldehydes and chloral hydrate formates, lactates and tartrates reducing sugars benzoquinone many amines uric acid. 

It is preferable to use Tollen s ammoniacal silver nitrate reagent, which is prepared as follows Dissolve 3 g. of silver nitrate in 30 ml. of water (solution A) and 3 g. of sodium hydroxide in 30 ml. of water (solution B). When the reagent is requir, mix equal volumes (say, 1 ml.) of solutions A and JB in a clean test-tube, and add dilute ammonia solution drop by drop until the silver oxide is just dissolved. Great care must be taken in the preparation and use of this reagent, which must not be heated. Only a small volume should be prepared just before use, any residue washed down the sink with a large quantity of water, and the test-tubes rinsed with dilute nitric acid. 

It must be noted, however, that nitroso, azoxy and azo compounds when subjected to the same treatment yield res])ectively hydroxylamines, hydrazo and hydrazine compounds, all of which reduce ammoniacal silver nitrate solution in the cold. 

Aromatic aldehydes react with the dimedone reagent (Section 111,70,2). All aromatic aldehydes (i) reduce ammoniacal silver nitrate solution and (ii) restore the colour of SchifiF s reagent many react with sodium bisulphite solution. They do not, in general, reduce Fehling s solution or Benedict s solution. Unlike aliphatic aldehydes, they usually undergo the Cannizzaro reaction (see Section IV,123) under the influence of sodium hydroxide solution. For full experimental details of the above tests, see under Ali-phalic Aldehydes, Section 111,70. They are easily oxidised by dilute alkaline permanganate solution at the ordinary temperature after removal of the manganese dioxide by sulphur dioxide or by sodium bisulphite, the acid can be obtained by acidification of the solution. 

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. 

Separated polyols are detected by a variety of reagents, including ammoniacal silver nitrate (175), concentrated sulfuric acid, potassium permanganate (163), lead tetraacetate, and potassium teUuratocuprate (176). A mixture of sodium metaperiodate and potassium permanganate can be used to detect as htde as 5—8 ).tg of mannitol or erythritol (177). 

Cyanamide is precipitated by excess ammoniacal silver nitrate as disilver cyanamide [3384-87-0] which is dissolved in acid and titrated with thiocyanate solution (27). 

In general, the carbonyl derivatives of isothiazole behave normally and condense readily with carbonyl reagents. The aldehydes reduce ammoniacal silver nitrate and undergo the Cannizzaro reaction. ... 

The free selenazole hydrazines are solids, sometimes well crystallized compounds. They show the typical properties of hydrazines. Thus they reduce Fehling s solution on warming and liberate silver, even in the cold, from ammoniacal silver nitrate solution. Further, they react with carbonyl compounds for example, benzylidene hydrazones are formed with benzaldehyde. These are identical with the hydrazones formed by direct condensation from benzaldehyde selenosemicarbazone and the corresponding a-halogenocarbonyl compound. 2-Hydrazino-4-phenylselenazole has also been reacted with acetophenone. The 2-a-methylbenzylidenehydrazone of 4-phenyl-selenazole (2, K = CJl, R" = H, R" = NH—N CMe-aH ) forms golden yellow plates mp 171°C. ... 

Chemical reduction is used extensively nowadays for the deposition of nickel or copper as the first stage in the electroplating of plastics. The most widely used plastic as a basis for electroplating is acrylonitrile-butadiene-styrene co-polymer (ABS). Immersion of the plastic in a chromic acid-sulphuric acid mixture causes the butadiene particles to be attacked and oxidised, whilst making the material hydrophilic at the same time. The activation process which follows is necessary to enable the subsequent electroless nickel or copper to be deposited, since this will only take place in the presence of certain catalytic metals (especially silver and palladium), which are adsorbed on to the surface of the plastic. The adsorbed metallic film is produced by a prior immersion in a stannous chloride solution, which reduces the palladium or silver ions to the metallic state. The solutions mostly employed are acid palladium chloride or ammoniacal silver nitrate. The etched plastic can also be immersed first in acidified palladium chloride and then in an alkylamine borane, which likewise form metallic palladium catalytic nuclei. Colloidal copper catalysts are of some interest, as they are cheaper and are also claimed to promote better coverage of electroless copper. 

If a group-specific reagent is now used, e.g. one that is chosen to react specifically with the reducing properties of aldehydes (ammoniacal silver nitrate solution) or to react with ketones (2,4-dinitrophenylhydrazine [9]) it is very simple to determine which form of alcohol is present in the sample. 

Reagent 2 Spray solution 2 Ammoniacal silver nitrate solution (precise composi-... 

An accident described with ammoniacal siiver chloride also occurs with ammoniacal silver nitrate, when kept for too long. Such a solution, which was kept for two weeks, detonated when it was stirred with a glass stirrer. Some authors vapourised such a solution when it was dry and isolated a solid, which proved to be explosive on impact. The structure of this (or these) compound(s), which is (or are) formed is not clearly defined. The authors, who proceeded to add sodium hydroxide containing ammonia to the solid, obtained a solid, which detonated almost immediately after its appearance in the solution. They considered it to be trisilver nitride. 

Propyne reacts with ammoniacal silver nitrate by forming a metallic derivative that detonates at 150°C. 

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