Silver azide sensitivity

Gray, P., Waddington, T.C. Defamation and decomposition of silver azide sensitized by the eyanamide ion. Chem. bid. 1255-1257 (1955)... 

Silver Azide. Silver a2ide, AgN, is prepared by treating an aqueous solution of silver nitrate with hydrazine (qv) or hydrazoic acid. It is shock-sensitive and decomposes violendy when heated. 

As a heavy metal azide, it is considerably endothermic (A// +279.5 kJ/mol, 1.86 kJ/g). While pine silver azide explodes at 340°C [1], the presence of impurities may cause explosion at 270° C. It is also impact-sensitive and explosions are usually violent [2], Its use as a detonator has been proposed. Application of an electric field to crystals of the azide will detonate them, at down to — 100°C [3], and it may be initiated by irradiation with electron pulses of nanosecond duration [4], See other catalytic impurity incidents, irradiation decomposition... 

Silver azide, itself a sensitive compound, is converted by ethereal iodine into the less stable and explosive compound, iodine azide. Similarly, contact with nitrogen-diluted bromine vapour gives bromine azide, often causing explosions. 

It is less sensitive and a less powerful explosive than silver azide or lead azide. It explodes on heating in air to above 270°C, or after an induction period at 140°C in the dark under vacuum. 

In order to construct the L-asparagine derivative of per-O-acetylated 0-(2-acetamido-2-deoxy-/ -D-glucopyranosyl( 1 — 4)-2-acetamido-2-deoxy-D-glucose (7), Spinola and Jeanloz (13) used (the sensitive) silver azide for conversion of the a-chloro anomer of the chitobiose derivative 8 into the / -azido derivative 9. Kunz and associates (14,15) have accomplished the conversion of the a-chloro anomer of 8 into 9 using sodium azide in the presence of tri-n-octyl-methylammonium chloride as a phase-transfer catalyst in chloroform water. 

Primary explosives differ from secondary explosives in that they undergo a rapid transition from burning to detonation and have the ability to transmit the detonation to less sensitive (but more powerful) secondary explosives. Primary explosives have high degrees of sensitivity to initiation through shock, friction, electric spark, or high temperature, and explode whether confined or unconfined. Some widely used primary explosives include lead azide, silver azide, tetrazene, lead styphnate, mercury fulminate, and diazodinitrophenol. Nuclear weapon applications normally limit the use of primary explosives to lead azide and lead styphnate. 

Silver solutions used in photography can become explosive under a variety of conditions. Ammoniacal silver nitrate solutions, on storage, heating or evaporation eventually deposit silver nitride ( fulminating silver ). Silver nitrate and ethanol may give silver fulminate, and in contact with azides or hydrazine, silver azide. These are all dangerously sensitive explosives and detonators [1], Addition of ammonia solution to silver containing solutions does not directly produce explosive precipitates, but these are formed at pH values above 12.9, produced by addition of alkali, or by dissolution of silver oxide in ammonia [2]. 

Sodium azide is not as sensitive as lead azide or silver azide to friction or mechanical shock. Since sodium azide reacts with metal oxides to generate nitrogen gas, mixtures of sodium azide and metal oxides are used as pyrolants in gas generators. However, sodium azide reacts with copper and silver to form the corresponding azides, both of which are detonable pyrolants. 

Silver is a white, ductile metal occurring naturally in its pure form and in ores (USEPA 1980). Silver has the highest electrical and thermal conductivity of all metals. Some silver compounds are extremely photosensitive and are stable in air and water, except for tarnishing readily when exposed to sulfur compounds (Heyl et al. 1973). Metallic silver is insoluble in water, but many silver salts, such as silver nitrate, are soluble in water to more than 1220 g/L (Table 7.3). In natural environments, silver occurs primarily in the form of the sulfide or is intimately associated with other metal sulfides, especially fhose of lead, copper, iron, and gold, which are all essentially insoluble (USEPA 1980 USPHS 1990). Silver readily forms compounds with antimony, arsenic, selenium, and tellurium (Smith and Carson 1977). Silver has two stable isotopes ( ° Ag and ° Ag) and 20 radioisotopes none of the radioisotopes of silver occurs naturally, and the radioisotope with the longest physical half-life (253 days) is "° Ag. Several compounds of silver are potential explosion hazards silver oxalate decomposes explosively when heated silver acetylide (Ag2C2) is sensitive to detonation on contact and silver azide (AgN3) detonates spontaneously under certain conditions (Smith and Carson 1977). 

It is a primary explosive and is slightly more sensitive to impact than Lead and Silver Azides. It would require 0.25g of this explosive to detonate lg of TNT... 

It is assumed that the presence of silver cyanide increases the sensitiveness of silver azide at elevated temperatures sensitized AgN3 explodes at a lower temperature than the ordinary compound and the induction period is shorter. 

The ignition temperature is 273°C and is thus much lower than that of lead azide, although the sensitiveness of silver azide to impact is also lower than that of lead azide. Taylor and Rinkenbach [124] report that with a 0.5 kg weight a 77.7 cm drop is necessary to cause detonation of silver azide, whereas for mercury fulminate a 12.7 cm drop is sufficient. 

To determine the sensitiveness to detonation of mining explosive in some countries (including Poland) special standard detonators have recently been introduced, containing 0.05, 0.1,0.t5, 0.20 g etc. of silver azide. The stronger contains 0.60 g of silver azide or an equivalent quantity of lead azide. 

Fig 19 The sensitization of silver azide to light due to the effect of gold particles (Ref 80). The dotted line corresponds to ignition for equal intensities the solid line shows the experimental curve. 

While pure silver azide explodes at 340°C,2 the presence of impurities may cause explosion at 270°C. It is also impact sensitive and explosions are usually violent/ Its use as a detonator has been proposed.4 Soluble in dilute nitric acid slightly soluble in... 

Photosensitizing Dyes. Many dyes cause explosions during thermolysis of dye-sensitized silver azide. 

Explosives used include azides, fulminates, diazo compounds, nitro or nitroso compounds, for example, lead or silver azide, mercury fulminate, lead styphnate, TNT, and PETN (which also act as sensitizers). 

Silver azide is sensitive to light, insoluble in water, and soluble in ammonia, from which it can be recrystallized. It is prepared from sodium azide and solutions of silver salts (depending on the working conditions) as a cheesy, amorphous precipitate. 

The commercial products, sporting paper caps (SPC potassium chlorate, red phosphorus and sulfur), toy paper caps (same components as SPC) and silver azide cartridges for breaking renal calculi have lower sensitivity than their powdery components because they are packaged as cartridges. 

Explosive reaction with acetylene, antimony powder, hafnium powder + heat, tetraamine copper(II) sulfate + ethanol, trioxygen difluoride (possibly ignition), polyacetylene (at 113°C). Forms sensitive, explosive mixtures with potassium (impact-and heat-sensitive), sodium (shock-sensitive), oxygen difluoride (heat-sensitive). Reacts to form explosive products with ammonia, ammonia + Uthium 1-heptynide, ammonia + potassium, butadiene + ethanol + mercuric oxide, silver azide. 

OSHA PEL TW A 0.01 mg(A /m3 ACGIH TLV WA 0.01 mg(Ag)/m3 DOT CLASSIFICATION Forbidden SAFETY PROFILE Explodes when heated above 270°C or on impact. Pure silver azide explodes at 340°. An electric field or irradiation by electron pulses can explode the crystals. Shock-sensitive when dry and has detonated 250°C. Solutions in aqueous ammonia explode above 100°C. Reacts to form more explosive products with iodine (forms iodine azide) bromine and other halogens. The presence of metal oxides or metal sulfides increases the azide s sensitivity to explosion. Mixtures with sulfur dioxide are explosive. When heated to decomposition it emits toxic fumes of NO,. See also AZIDES and SILVER COMPOUNDS. 

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