Incidents explosion, azide

Ammcan Industrial Hygiene Association. Laboratory Health and Safety Committee. Laboratory Safety Incidents. Phenyl Azide Compound Erupts During a Vacuum Distillation available at http /Avww2. umdnj.edu/edissweb/aiha/accidents/explosion.htm Phenyl%20Azide (accessed September 22, 2009). 

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... 

A few diazonium salts are unstable in solution, and many are in the solid state. Of these, the azides, chromates, nitrates, perchlorates (outstandingly), picrates, sulfides, triiodides and xanthates are noted as being explosive, and sensitive to friction, shock, heat and radiation. In view of their technical importance, diazonium salts are often isolated as their zinc chloride (or other) double salts, and although these are considerably more stable, some incidents involving explosive decomposition have been recorded. 

Trituration of the crude cw-azide with hexane at ambient temperature caused detonation to occur. Isolation of low molecular weight carbonyl azides should be avoided, or extreme precautions taken. A similar incident with the analogous cyclobutane diazide was reported [1], During use as an intermediate in preparation of the 1,2-diamine, the explosive diazide was never isolated or handled free of solvent [2]. The trans isomer (0.25 mole) was prepared by the latter technique, but as a 45 w/v% solution in toluene, rather than as the recommended 10% solution. When a magnetic spin-bar was introduced, the solution detonated. Initiation may have involved friction from adventitious presence of iron filings adhering to the magnetic bar [3],... 

Although this distillation has been conducted repeatedly without incident, azides are potentially explosive.3 Consequently, the distillation should be conducted behind a safety shield and the operator should wear protective equipment. The distilling flask should be heated by means of a water bath to avoid the possibility of overheating the distillation residue. 

Explosions also occur frequently during the compaction of lead azide in detonator cups, and Wythes [3] reported 140 such incidents in ordnance factories in Britain during the aforementioned period. A typical figure for high-volume production in an ammunition plant in the U.S.A. is 232 incidents with 1,000,000 detonators. Mechanical and electrostatic stimuli and human failure were blamed for many of these accidents, but in these cases, as with those encountered during manufacture, no loss of life or injuries resulted because of protective structures. 

INCIDENT 3.2.2.1 DIMETHYL SULFATE AND SODIUM AZIDE EXPLOSION ... 

During the preparation of methyl azide from dimethyl sulfate and sodium azide, an explosion occurred. The same reaction had previously been carried out without incident. Upon investigation, the chemists found that Bretherick s Handbook of Reactive Chemical Hazards reported that this reaction can result in an explosion if the acidity of the solution drops to pH 5. It was surmised that sodium hydroxide, which was added to maintain the pH above 7, was not added at a sufficient rate to keep the solution at the required pH. Further steps (visible color indicator) were taken in subsequent preparations to ensure that the pH was maintained in the appropriate range. 

Caution. Although we have carried out this preparation without incident several times, copper azides, which are explosive, are intermediates in this reaction. This preparation should be conducted behind a safety shield. Pure 1,1 -diazidoferrocene has been reported to explode when heated rapidly above its melting point o/56°C. ° We strongly recommend carrying out the hydrogenation of l,r-diazidoferrocene without isolating it from its ether solutions. 

The liberated azoimide attacks copper or its alloys (brass) and copper azides form on the metal surface. The concurrent use of LA and copper (or brass) in fuses or blasting caps therefore represents an inherent safety hazard. Although the LA-copper (copper alloys) reaction has been known since 1913, it has been a cause of many incidents decades later [49]. These incidents have been sometimes erroneously reported as spontaneous explosions. The reality, however, is that, in all known cases, they have been linked to some type of movement and therefore should not be considered spontaneous [70]. 

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