Explosives lead picrate

During the traditional qualitative inorganic analytical procedure, samples containing the lead and salicylate radicals can lead to the formation and possible detonation of lead picrate. This arises dining evaporation of the filtrate with nitric acid, after precipitation of the copper-tin group metals with hydrogen sulfide. Salicylic acid is converted under these conditions to picric acid, which in presence of lead gives explosive lead picrate. An alternative (MAQA) scheme is described which avoids this possibility. 

Qualitative inorganic analysis of compounds containing lead and salicylate radicals can lead to the formation of explosive lead picrate. This occurs due to conversion of salicylic acid to picric acid during evaporation with nitric acid.21... 

VI. Uses. During the latter part of the nineteenth century and the early part of the present century, PA was widely used as the main expl charge of projectiles and bombs. This is no longer true, Indeed PA per se is hardly used as an expl. Its current limited expl-related use is primarily in the preparation of Explosive D (Ammonium Picrate) and Lead Picrate. It also finds some use as an intermediate in the manuf of dyes. There is some patent literature on the use of PA as a catalyst for polymerizations. For example, PA is claimed as catalyst in polybutadiene polymerizations (Ref 40), and for the prepn of an isobutylene-5-methyl-1,3,6 hepta-trieie copolymer (Ref 38)... 

A violent explosion of Picric Acid in a Manchester factory in 1887 was ascribed to the formation of picrates. Burning, molten Picric Acid flowed down onto lithopone, forming lead picrate which in consequence caught fire. The latter, being an initiator, detonated and caused the Picric Acid to detonate... 

Figure A. 103 Lead picrate primary high explosive.

Fig. 49. Diagram of the design and operation of a reactor for the manufacture of lead azide and other primary explosives (tetrazene, lead styphnate and lead picrate).

T. Urbanski and Kruszynska [41] made a comparative study of the sensitiveness to impact of lead picrate and other initiating explosives. They found lead picrate to be more sensitive than any other substance. They also examined the decomposition of lead picrate on hot metal plates. On contact with a metal surface heated to 341 °C it explodes after 3 sec, and on one heated to 370°C after 1 sec. 

Detonators were manufactured abroad and sold for a time under Nobel s patent, A. V. Newton (from A. Nobel, Paris), Brit. Pat. 16,919 (1887), covering the use, instead of fulminate, of a granulated mixture of lead picrate, potassium picrate, and potassium chlorate, but the invention apparently contributed little to the advance of the explosives art. 

Nowadays the only picrates applied as explosives for military purposes are ammonium and lead picrates, the latter being an initiating explosive (Vol. III). 

Lawinit = slurry (Austria) 195 LDNR = lead dinitroresorcinate LE = low explosive propellant (UK) lead acetyl salicylate 164 196 328 lead azide 23 43, 144 196 328 lead block test 197 301 343 lead ethylhexoate 164 200 328 lead nitrate 201 328 lead picrate 201 lead salicylate 164 lead stearate 164 lead styphnate 29 43, 202 328 lead sulfate 164 174 lead trinitroresorcinate = lead styphnate 29 43 202 328 leading lines 203... 

Dry the material using a hot water bath. Place the lead picrate in an acid-resistant container and set the container in a pan of hot (90°C/194°F) water. WARNING This material is a primary explosive—it must be handled very gently. 

There is little information readily available on lead picrate. However, it is a workable primary explosive. This material is not very powerful and should always be used with a booster charge of an easily detonated secondary explosive. Like all primary explosives, this material is very sensitive to impact, friction, and sparks. 

General Recommendation 6. Simultaneous processing of different types of energetic materials should not be performed until there is substantial evidence that the intermediates formed from the hydrolysis of aromatic nitro compounds will not combine with M28 propellant additives or ordnance fuze components to form extremely sensitive explosives, such as lead picrate (see General Finding 4). 

Only a small amount of PA was observed in the solids formed during the tetrytol testing (O Neil, 2001). However, if a mixed feed stream containing an aromatic nitro compound (Composition B and tetryl or tetrytol) is processed with a propellant that contains lead, lead picrate (a very sensitive primary explosive) can be formed. During the M28 propellant tests, lead dioxide precipitated on the cell membrane, so it is possible that the precipitation of lead with the small amount of picric acid that might be present does not compete with the formation of lead dioxide in the electrochemical cell. However, the possibility of lead picrate precipitation cannot be dismissed a priori. A determination of the relative solubilities of lead dioxide and lead picrate in nitric acid solutions could provide some insight into whether the formation of lead picrate is likely to be a problem for mixed feeds. 

Lead picrate is used as a primary explosive in the fabrication of detonators (section 6.13). It is to be used with a booster explosive such as picric acid (section 1.21) or RDX (section 1.15). 

Picric acid can be used as a booster explosive in detonators (section 6.13). a high explosive charge, or as an intermediate to preparing lead picrate (section 1.20) or DDNP (section 1.19). 

Lead picrate is considered highly sensitive to mechanical impact and thermal stimuli [6]. The anhydride is more sensitive to mechanical stimuli than the hydrates. Impact sensitivity of anhydride is significantly higher than the sensitivity of mercury fulminate (4 cm/0.5 kg vs. 24 cm for MF) [7,8]. Handling of lead picrate anhydride represents the same level of risk as handling of lead styphnate. The ignition temperature is 281 °C (explosion takes place instantaneously or within 1 s) [7]. The formation of lead picrate by reaction of tetryl (which decomposes to picric acid) with lead azide is reported as a possible reason for the higher sensitivity of this mixture compared to pure LA [6]. 

Lead picrate forms several basic salts with varying lead content. They form citric yellow crystals practically insoluble in water or alcohol. Its explosive properties are similar to those of lead styphnate but its flammability is lower [10]. Sensitivity to electrostatic discharge is high (at the level of LS) and is the reason for the many accidents which occurred during its manufacture [12]. Sensitivity to impact is 2.5 J (it explodes by 5 kg hammer from 5 cm) [13]. 

Basic lead picrate is prepared by reaction of picric acid with yellow lead oxide in water. The mixture is stirred and boiled during the reaction. Product forms as a precipitate [11]. Basic lead picrate has similar explosive properties to those of LS and was therefore used in similar applications (e.g., as a component of percussion mixtures) [10-12]. Due to its lower flammability, it was, however, replaced in practical use by LS [12]. 

If, however, the material is concentrated in a small area or when it is in a confined space, explosion may occur. Burning Picric Acid containing metal picrates may result in explosion. Similarly a potential danger exists when burning Picric Acid is in contact i ith metals, since in the molten state it forms picrates which may initiate explosion. This depends largely on the metal lead, iron, copper should be considered particularly dangerous ... 

Picric acid, in common with several other polynitrophenols, is an explosive material in its own right and is usually stored as a water-wet paste. Several dust explosions of dry material have been reported [1]. It forms salts with many metals, some of which (lead, mercury, copper or zinc) are rather sensitive to heat, friction or impact. The salts with ammonia and amines, and the molecular complexes with aromatic hydrocarbons, etc. are, in general, not so sensitive [2], Contact of picric acid with concrete floors may form the friction-sensitive calcium salt [3], Contact of molten picric acid with metallic zinc or lead forms the metal picrates which can detonate the acid. Picrates of lead, iron, zinc, nickel, copper, etc. should be considered dangerously sensitive. Dry picric acid has little effect on these metals at ambient temperature. Picric acid of sufficient purity is of the same order of stability as TNT, and is not considered unduly hazardous in regard to sensitivity [4], Details of handling and disposal procedures have been collected and summarised [5],... 

Metal salicylates are occasionally incorporated into mixtures of unknowns for qualitative inorganic analysis. During the conventional group separation, organic radicals are removed by evaporation with nitric acid. When salicylates are present, this can lead to formation of trinitrophenol through nitration and decarboxylation. This may react with any heavy metal ions present to form unstable or explosive picrates, if the evaporation is taken to dryness. The MAQA alternative scheme of analysis obviates this danger. 

Trinitrophenol (4), commonly known as picric acid (VOD 7350 m/s, d = 1.71 g/cm ), was once used as a military explosive although its highly acidic nature enables it to readily corrode metals. This kind of reaction has led to many fatal accidents, a consequence of some metal picrates being very sensitive primary explosives. The lead salt of picric acid is a dangerous explosive and should be avoided at all cost. In contrast, the ammonium (Explosive D, VOD 7050 m/s, d = 1.60 g/cm ) and guanidine salts of picric acid are unusually insensitive to impact and have been used in armour piercing munitions. 

The hot gases from the percussion primer permeate thru the baffle and initiate the BkPdr delay pellet, which burns under the reproducible pressure conditions which are obtained within the delay element housing, with a delay time of 0.035 sec. When the BkPdr element has burned thru, a spit of flame impinges on a detonator loaded with LA a true detonation develops and progresses successively thru the Tetryl-loaded lead-out, the Tetryl-loaded booster lead-in, the Tetryl-loaded booster and Explosive D (Ammonium Picrate) -loaded main (or bursting) charge of the projectile. 

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