246Trinitroresorcinol

246-Trinitroresorcinol, also known as 2,4,6-trinitroresorcinol or picric acid (historically referred to as *caramel acid*), is an organic compound with the chemical formula C₆H₃N₃O₇. It is a yellow crystalline solid that belongs to the class of nitroaromatic compounds and is notable for its explosive properties. The compound was first synthesized in 1841 by the German chemist Justus von Liebig, though its explosive potential was not immediately recognized.

Picric acid is characterized by its high nitrogen content (approximately 18.5%) and its ability to form stable salts with various metals, such as potassium (potassium picrate), which enhances its explosive sensitivity. It was widely used as a military explosive during the late 19th and early 20th centuries, particularly in shell fillings and grenades, due to its high detonation velocity and stability compared to other explosives like nitroglycerin. However, its sensitivity to friction and impact, as well as its tendency to corrode metal containers, limited its practical applications.

Beyond its explosive uses, picric acid has found applications in analytical chemistry as a reagent for detecting certain metal ions, such as aluminum and thorium. It also serves as a yellow dye in some historical textile applications. Due to its corrosive nature and potential hazards, its use has declined in favor of safer alternatives in modern industrial and military contexts.

The compound is classified as a hazardous material, requiring careful handling due to its explosive and toxic properties. Its storage and disposal must comply with strict safety regulations to prevent accidents or environmental contamination. Picric acid remains a subject of interest in both historical and contemporary studies of explosives and organic chemistry.