Acetylides and Fulminates

Acetylides and fulminates form highly explosive shock- and heat-sensitive salts with many metals. Acetylides are the metal derivatives of acetylene. Hydrogen attached to carbon atoms bearing a triple bond is acidic in nature. It can be substituted by a metal ion to form acetylides, with the general structure M-C=C-M. These substances are made from acetylene, HC=CH, or alkyl acetylene, RC=CH, by passing acetylene gas or aUcyl acetylene vapors over the aqueous solutions of ammoniacal metal salts, as shown in the following reactions  

An alkyne of the type RC CH would yield a monocopper derivative. The acetylide 

A Comprehensive Guide to the Hazardous Properties of Chemical Substances, by Pradyot Patnaik Copyright 2007 John Wiley Sons, Inc. 

Hazardous properties of some selected acetylides and fulminates are presented in the following sections. 

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Explosions involving flammable gases, vapours and dusts are discussed in Chapter 5. In addition, certain chemicals may explode as a result of violent self-reaction or decomposition when subjected to mechanical shock, friction, heat, light or catalytic contaminants. Substances containing the atomic groupings listed in Table 6.7 are known from experience to be thermodynamically unstable, or explosive. They include acetylides and acetylenic compounds, particular nitrogen compounds, e.g. azides and fulminates, peroxy compounds and vinyl compounds. These unstable moieties can be classified further as in Table 6.8 for peroxides. Table 6.9 lists a selection of potentially explosive compounds. 

This class of compounds showing explosive instability deals with heavy metals bonded to elements other than nitrogen and contains the separately treated groups GOLD COMPOUNDS LEAD SALTS OF NITRO COMPOUNDS LITHIUM PERALKYLURANATES MERCURY COMPOUNDS METAL ACETYLIDES METAL FULMINATES METAL OXALATES PLATINUM COMPOUNDS PRECIOUS METAL DERIVATIVES SILVER COMPOUNDS... 

Nitrogen halides are destroyed with cold base. Azides and fulminates-may often be destroyed with acid, while heavy metal acetylides are decomposed by ammonium sulfide. The removal of peroxides by reduction has been described above. 

Flammability and Explosibility Silver and most soluble silver compounds are not combustible. However, silver nitrate and certain other silver compounds are oxidizers and can increase the flammability of combustible materials. Silver acetylide, azide, fulminate, oxalate mixtures, styphnate, tartarate mixtures, and tetrazene are all explosives and must be handled as such. 

Acetylides of heavy metals (silver, copper, gold, mercury) do not react with moisture and are stable in contact with air. These acetylides are very sensitive to mechanical stimuli and have the characteristics of primary explosives. Their explosive power is considered to be the same as that of azides and fulminates [2]. 

Only one of the acetylides(cuprous acetylide) has found application in industry as an ingredient of electric detonators. Some acetylides, as for instance, that of silver, arc probably suitable for use in primers and detonators. They also may be incorporated in LA-based compositions for expl rivets in order to reduce their ignition point(Ref 6) According to Sax(Ref 6) the toxicity of acetylides is unknown, but their expln hazards are considered to be the same as those of fulminates and azides. The acetylides must be handled with extreme care and In storage they must be kept cool and wet. Metal powders, such as finely divided Cu or Ag, should be excluded. Shipping regulations are the same as for other primary and initiating explosives Refs l)Beil 1,238-40,(104 6),[217-20] ... 

Silver acetyUde. Although silver acetylide has not received practical appli cation it has been the subject of a few published papers. Stcttbacher [165] was first to draw attention to the very strong initiating properties of silver acetylide. He found that th initiating charge is 0.07 g (for AgNj and mercuric fulminate he found figures of 0.02 g and 0.29 g respectively). 

The electron bombardment of explosives has been undertaken by various investigators in an effort to initiate or decompose the material under study. One of the early investigations was undertaken by Kallmann and Schrankler [30], who bombarded TNT, mercury fulminate, nitrocellulose, and to some extent, picrates and azides with 10-kV, 1-mA electrons in vacuo but were unable to produce explosions. However, when heavy ions of argon and mercury were used, initiations were achieved with several substances with each of the ions. Muraour [31 ] subjected lead azide and silver acetylide to 90 kV at 3 mA for 3 min and only achieved explosion with silver acetylide. Both explosives blackened upon electron irradiation. Muraour believed that the explosion was either a thermal effect or that, by chance, a sufficiently large number of molecules decomposed at one point to bring about complete decomposition. 

MERCURY(n) NITRATE (10045-94-0, anhydrous 7783-34-8, monohydrate) Hg(N03)2 H,0 Noncombustible solid. Light sensitive. A powerful oxidizer accelerates the burning of combustible materials. Violent reaction, or may form explosive materials, with reducing agents, including hydrides, nitrides, phosphorus, stannous chloride, and sulfides alkyl esters (forms explosive alkyl nitrates) combustible materials (especially if finely divided), phosphinic acid, hypophosphoric acid, metal powders petroleiun hydrocarbons. Forms heat- and/or shock-sensitive compounds with acetylene (forms explosive mercmy acetylide), ethanol and other alcohols (may form explosive mercury fulminates), ferrocene, isobutene, phosphine gas (forms heat- and shock-sensitive precipitate) potassiiun cyanide, sulfur. Incompatible with strong acids, acetic anhydride, ammonia, ammonium hexacyanofenate(II), organic azides, citric acid, hydrazinium perchlorate, isopropyl chlorocarbonate, nitrosyl perchlorate, sodium thiosulfate, sulfamic acid, thiocyanates, hydrozoic acid, methyl isocyanoacetate, sodium peroxyborate, trinitrobenzoic acid, urea nitrate. Aqueous solution corrodes metals. 

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