Silver nitrate ammoniacal, preparation

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. 

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. 

During preparation of an oxidising agent on a larger scale than described [1], addition of warm sodium hydroxide solution to warm ammoniacal silver nitrate with stirring caused immediate precipitation of black silver nitride which exploded [2], Similar incidents had been reported previously [3], including one where explosion appeared to be initiated by addition of Devarda s alloy (Al—Cu—Zn) [4], The explosive species separates at pH values above 12.9, only produced when alkali is added to ammoniacal silver solutions, or when silver oxide is dissolved with ammonia [5], The Sommer Market reagent mixture used to identify cellulose derivatives led to a severe explosion [6],... 

A more careful investigation was made by Perry et al. (14). In their experiments, a buffered silver sol prepared by dextrose reduction of ammoniacal silver nitrate was mixed with a solution of hydroquinone in a hydrogen atmosphere. Both solutions were deaerated before mixing. The mixed solution was stirred with hydrogen for one-half hour, then pressed through an ultrafilter under hydrogen pressure. The filtrate was analyzed for hydroquinone, and correction was made for retention of hydroquinone by the filter membrane. A small amount of... 

Aldonic and ketoaldonic acids may be difficult to separate. Norris and Campbell separated ketogluconic acid from gluconic acid by preparing the phenylhydrazone of the keto acid, which is then easily separable from gluconic acid. A methanol-ethanol-water solvent mixture was used.64 Another useful solvent developer is 1-butanol-formic acid-water.133 Macek and Tadra separated a series of ketoaldonic acids in a number of acidic solvent developers.134 Color reagents which may be used include ammoniacal silver nitrate,94 o-phenylenediamine dihydrochloride,84 and aniline acid oxalate.138 Lactones are detectable with hydroxylamine followed by ferric chloride.128... 

Caution Ammoniacal Silver Nitrate TS forms explosive compounds on standing. Do not store this solution, but prepare a fresh quantity for each series of determinations. Neutralize the excess reagent and rinse all glassware with hydrochloric acid immediately after completing a test. 

Z-Eburnamonine (XXXVI) has been produced by other reactions of vincamine. Oxidation of vincaminic acid (XL R = H) by means of ammoniacal silver nitrate was one way, and periodic acid fission of vincaminol was another (16). A different group of workers, who had probably attempted to prepare vincaminol by lithium aluminum hydride reduction of vincamine, obtained instead Z-ebumamonine in excellent yield (18). This has been rationalized as illustrated (partial formulas) by analogy with the base-induced decomposition of formic esters to carbon monoxide and alkoxide ion ... 

An alternative method for carrying out the silver mirror test is the following. Prepare ammoniacal silver nitrate solution by placing 5 ml silver nitrate solution in a thoroughly clean test-tube and add 2-3 drops of dilute sodium hydroxide solution add dilute ammonia solution dropwise until the precipitated silver oxide is almost redissolved (this procedure reduces the danger of the formation of the explosive silver azide, AgN3, to a minimum). Introduce about 0-5 ml neutral tartrate solution. Place the tube in warm water. A silver mirror is formed in a few minutes. 

D) Formation of Metallic Acetylides. Pass acetylene gas for one minute into 5 ml of each of the solutions of ammoniacal silver nitrate and ammoniacal cuprous chloride, prepared according to directions given below. Note the character of the precipitate. Disconnect the flask, and dispose of the material in the flask, according to directions given by the instructor. 

The ammoniacal silver nitrate is prepared by the addition of ammonium hydroxide to 2 ml of 0.1 N silver nitrate until the precipitate which forms just redissolves. Sufficient water is added... 

A much smaller micropipette silver electrode was prepared for chloride measurements by Kerkut and Meech (37). They introduced a concentrated ammoniac silver nitrate solution into borosilicate glass micropipettes and kept the micropipettes for 10 hours in 20% formaldehyde solution. The formaldehyde diffusing into the narrow opening reduced the silver and formed a metallic silver plug inside the tip of the micropipette. Silver chloride-coated silver wire was used as inner reference electrode in the silver nitrate internal filling solution. 

General directions for preparation of thiouronium salts 620 Equimolar amounts of thiourea and alkyl halide are heated on the water-bath in a volume of alcohol equal to that of the halide, until treatment of a sample with ammoniacal silver nitrate no longer gives a precipitate of silver sulfide. 

The amount of sulphides may ho estimated by titrating the hot soda solution, to which ammonia has been added, with an ammoniacal silver nitrate solution, I c.c. of which corresponds to 0 005 gramme Na. S. As the titration proceeds, the precipitate is filtered off, and the addition of ammoniacal silver solution to the filtrate continued until a drop produces only a slight opacity. The presence of chloride, sulphate, hydrate, or carbonate does not interfere with the accuracy of this method. The ammoniacal silver nitrate solution is prepared by dissolving 13 345 grammes of pure silver in pure nitric acid, adding 250 c.c. liquor ammoniie fortis, and diluting to 1 litre. 

Use anal tech silica gel GF plates (20 X 20 cm) impregnated by dipping into ammoniacal silver nitrate solution for atrazine and 2,4-D. Prepare the dip solution by mixing 216 ml of fresh silver nitrate stock solution (17 g of AgNOi dissolved in 25 ml of deionized water, made up to 1 L with acetone), 20 ml of deionized water, and 6 ml of 6 M ammonium hydroxide. Dip for several seconds. 

Ammoniacal Silver Nitr. te. Add 1 drop of 10% aqueous NaOH solution to about 5 ml. of silver nitrate solution in a test-tube then add dilute NHg drop by drop with shaking until only a trace of undissolved Ag O remains. A number of reductions require the presence of Ag " ions. It is often advisable, therefore, after adding the ammonia to add silver nitrate solution until a faint but permanent precipitate is obtained. The solution should always be prepared in small quantities immediately before use, and any unexpended solution thrown away afterwards. If the solution is kept for some time, it may form explosive by-products. 

Do not heat the silver solution or allow it to stand even for a few hours, since explosive silver fulminate may be formed. The ammoniacal solution of silver nitrate is prepared by treating 3 ml. of 0-lN silver nitrate solution with very dilute ammonia solution dropwise until the precipitate which is first formed just redissolves. 

Ammoniacal silver oxide is as dangerous as the previous similar compounds. Thus, the clear solution, which is obtained after centrifuging ammoniacal silver oxide leaves a very explosive compound as a residue to which was attributed the AgaN4 formula. It seems that the decomposition of this nitride is inhibited by ammonium salts. A similar situation was created after treating this ammoniacal oxide with silver nitrate until a solid started to precipitate, and this detonated 10 to 14 days after being prepared. It was assumed that this solid was AggNH. 

A. J. Balard 8 prepared an olive-green insoluble mass by the action of bromine water on copper oxide, vegetable colours are not bleached, but nitrogen is evolved from ammonia, and carbonic and other acids set free bromine. When heated, oxygen, bromine, and water are given off, and copper oxybromide remains. The solid is possibly a mixture of bromine and copper oxybromide and not copper hypobromite. A. J. Balard also prepared a soln. which probably contained silver hypobromite by the action of bromine water on silver oxide. The product easily decomposes into bromide and bromate. F. W. Schmidt suggested that the white floccuient precipitate obtained by the action of iodine on a very dil. ammoniacal soln. of silver nitrate is possibly silver hypoiodite. 

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