picrate

Picrate is the name given to any salt derived from picric acid, or 2,4,6-trinitrophenol. In practice, picrates are salts formed when the acidic hydrogen of picric acid is replaced by a metal or ammonium cation, producing salts such as potassium picrate, sodium picrate, ammonium picrate, and silver picrate. The term may also refer to the picrate anion itself in some contexts.

Chemically, picric acid is a highly acidic nitroaromatic compound, with its acidity enhanced by the three nitro groups. The picrate anion that forms upon deprotonation is stabilized by resonance with the electron-withdrawing nitro groups, and the resulting salts commonly appear as yellow to orange crystalline solids. Solubility and stability of picrate salts vary with the cation and hydration state.

Historically, picric acid and its salts have played important roles as dyes and as energetic materials. Picric acid was widely used in textiles and paper dyes in the 19th and early 20th centuries, and various picrate salts have been employed as explosives or energetic components in primers and detonators. Today, picrate salts are primarily of interest in the study of energetic materials and related chemistry, with specific handling largely restricted to appropriate laboratories.

Safety considerations are central to picrates: they are oxidizing and, in dry form, can be highly sensitive to shock, friction, and heat. Proper storage, handling, and disposal require specialized facilities and procedures to minimize risk.