Silver fulminate preparation

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. 

Silver fulminate must invariably be destroyed immediately after it is prepared. This is most readily done vrith hydrochloric acid. 

Among other fulminates, the silver salt, (CNO)2Ag, is of some importance. It is prepared in a way similar to mercury fulminate, by the action of alcohol on a silver solution in nitric acid. Silver fulminate, however, is of little value as an explosive since silver is an expensive raw material. Detonators of silver fulminate were employed only in the Italian Navy. 

These compounds, however, have not been used in practice (apart from silver fulminate, as mentioned above) due to the high cost of preparing them. 

Fulminating silver was prepared in 1788 by Berthollet who precipitated a solution of nitrate of silver by means of lime water, dried the precipitated silver oxide, treated it with strong ammonia water which converted it into a black powder, decanted the liquid, and left the powder to dry in the open air. Fulminating silver is more sensitive to shock and friction than fulminating gold. It explodes when touched it must not be enclosed in a bottle or transferred from place to place, but must be left in the vessel, or better upon the paper, where it was allowed to dry. 

Tollen s test The reagent should be freshly prepared by mixing two solutions (A and B). Solution A is a 10% aqueous AgNOs solution and solution B is a 10% aqueous NaOH solution. When the test is required, 1 ml of solution A and 1 ml of solution B are mixed, and the silver oxide thus formed is dissolved by dropwise addition of 10% aqueous NH4OH. To the clear solution, 10 drops of the compound to be tested are added. A silver mirror is indicative of the presence of an aldehyde. The reagent mixture (A + B) is to be prepared immediately prior to use otherwise, explosive silver fulminate will form. The silver mirror is usually deposited on the walls of the test tube either immediately or after a short warming period in a hot water bath. This is to be disposed of immediately with diluted HN03 (detection limit, 50 mg compounds tested, Q to C6). 

Silver fulminate is prepared by the reaction employed in the preparation of - Mercury Fulminate, i.e., by reacting a solution of silver in nitric acid with alcohol. Like mercury fulminate, it is also toxic. 

Summary Silver fulminate is prepared in a similar fashion as the mercury salt by the addition of a hot nitrate acid solution upon ethyl alcohol. In this case, silver nitrate is dissolved in nitric acid, the mixture is then heated, and the ethanol dropped in. As the reaction proceeds, the silver fulminate will precipitate. It is then easily filtered-off, washed, and dried. Note Various modifications to this procedure exist. 

Other metallic fulminates cannot be synthesized directly by reaction of metal with nitric acid and sequentially with ethanol in the same way as mercury or silver fulminates (and probably also complex Na[Au(CNO)2]). They are therefore mostly prepared by reaction of mercuric fulminate with the relevant amalgam. 

Silver fulminate (SF) is a white crystalline material with heat of formatiOTi 179 kJ mol [15]. It crystallizes in the form of small rosettes or star-shaped clusters. Two polymorphic forms have been reported—orthorhombic and trigonal. The crystal shape depends on reaction conditions (temperature, concentration) during sUver fulminate preparation [94]. Recrystallization from ammonia leads to needles and multiple growths of leaf-like habits [92]. Long (4—5 mm) needle-shaped crystals were prepared by Singh and investigated by X-ray analysis. It was found that the crystal is orthorhombic [95]. The crystal structure of SF was later investigated in detail by Britton and Dunitz [96, 97] and their results were confirmed by Barrick et al. [98]. Ammonium acetate solution ( 20 %) is recommended as the solvent for... 

Silver fulminate is considered as an extremely dangerous primary explosive to handle due to its high sensitivity, particularly to electric discharge and friction. It is more sensitive than MF with respect to both of these initiation stimuli. The sensitivity to electric discharge is extreme, particularly when it is dry [92]. The sensitivity of silver fulminate depends on its crystal form the amorphous form is less sensitive to impact than the crystalline form. However, since it is practically impossible to produce purely amorphous material without any crystals the whole mass might be nearly as sensitive as the crystalline form itself [29]. Taylor and Buxton published preparation of SF in form of fine crystals with an impact sensitivity significantly lower than MF (no explosion from 32.7 cm for 1/2 kg hammer vs. only 12.7 cm for MF) approaching values typical for lead azide [93]. Comparison of impact sensitivity of SF with other common primary explosives is shown in Fig. 2.15. 

Preparation of silver fulminate is similar to the preparation of MF. Silver is dissolved in nitric acid after which the solution is poured into ethanol [14, 29, 33, 35, 93]. The reaction mechanism is the same as in the case of MF and the overall reaction may be simplified by the following equation ... 

Silver fulminate also forms when passing nitrogen oxide gas through an ethanol solution of silver nitrate [35, 42]. Other methods of SF preparation are almost analogous to preparation of MF (see Sect. 3.1.2.7). 

In contrast to mercury and silver fulminates, most other metallic fulminates are too sensitive, or physically or chemically unstable. Further, their preparation is too expensive and demanding for practical use. Many fulminates are hygroscopic stable when dry but decompose in presence of carbon dioxide when moist (cadmium, copper(I), copper(n), thaUium) [15, 29, 57, 106]. 

The majority of fulminates (except those of SF and MF) are prepared by reaction of relevant amalgam of less noble metal with mercury (or silver) fulminate in methanol or ethanol and precipitated by diethyl ether [29, 39, 57,106, 107, 114]. 

Sensitivity of silver azide to impact is several times lower than that of mercury fulminate. Comparison with lead azide is reported a little bit higher than LA by some authors [45] (Bureau of Mines) [82], same as LA [45] (Picatinny Arsenal Apparatus), or lower than LA by others [21, 81] (see Fig. 2.15). The sensitivity of SA highly depends on crystal size and shape. Colloidal silver azide prepared fi om concentrated solutions exhibits significantly lower sensitivity (0.5 kg from 77.7 cm) than coarser crystals prepared fi-om diluted solutions which required less than half the energy (0.5 kg... 

Fully reversed fatigue test, 13 489 Fulminating silver, 22 674 Fumarate, in silicone network preparation, 22 566... 

Silver Azide, Cadmium Azide, Cupric Azide, Triazidotrinitrobenzene, Chloratotrimercuraldehyde, Nitrogen Suifide Hexamethylenetriperoxidediamine Until WWI, Mercuric Fulminate was the principle initiating agent used, but Lead Azide has now replaced it. Lead azide is not the most powerful azide, but is more stable and less dangerous to handle than some of the other ones. Cadmium Azide, for example, is more powerful than Lead Azide but is unsuitable as an initiating agent because it is difficult to prepare and is soluble in water... 

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