Guanidines picrate salts

The same kind of stabilization is present in monosubstitued guanidines and thus in the arginine side chain as well. The free base can be obtained with help of sodium methoxide and once formed it is subject to acylation. In protonated form, however, the guanidine group is inert toward acylating agents and can be left without further blocking. Yet, the commonly applied hydrochloride form lends unfavorable solubility properties to the intermediates. This is less pronounced in the picrate salts and, therefore, blocked and activated intermediates, such as... 

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. 

CA 54, 15934(1960) (Differential thermal analysis and thermograwimetry of some salts of Gu and related compounds) (Compares thermal stability, deton temp and 5-kg impact sensitivity of Picrates and Styph-nates of Hydrazine, aminoguanidine, N-methyl-guanidine, guanylurea, N-ethylguanidine and Gu)... 

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