Normal Lead Picrate

Normal lead picrate forms several hydrates containing from 1 to 5 molecules of crystal water. The tetrahydrate of lead picrate is obtained when an aqueous solution of picric acid is treated with lead carbonate. The monohydrate results when the tetrahydrate is retained at 80 °C and also when the anhydride is exposed to air. The anhydrous salt is obtained when the tetrahydrate or monohydrate is heated to 150 °C [4]. 

The tetrahydrate forms silky yellow needles while the anhydride forms a yellow powder [4]. Lead picrate is insoluble in water, ether, chloroform, benzene, and toluene sparingly soluble in acetone and alcohol [5]. 

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]. 

Neutral lead picrate is prepared by reaction of aqueous solutions of picric acid [5,9, 10] or mixture of picric acid and its sodium salt [5] with lead nitrate or acetate. Lead picrate is isolated as a yellow precipitate. 

Lead picrate was used in applications similar to those for lead styphnate, for example, as part of ignition mixtures in fuses during World War II [8, 9]. Lead 

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Although precipitation of lead picrate is not likely to be a hazard during normal operation of a well-designed hydrolysis reactor, some data are still unavailable. During the hydrolysis runs at Holston, the material balance for lead was extremely poor. None of the runs of Ml propellant, each of which contained a little less than 4 pounds of lead in the feed, indicated any lead in the end-of-run hydrolysate analysis. Also, no lead was identified in the solids remaining at the end of any of the hydrolysis reactions. The inability to account for... 

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