Study of picrate salts with amines

The reaction of picric acid (2,4,6-trinitrophenol) with amines [urea, cyclohexane-1,2-diamine, 1H-1,2,4-triazole-3,5-diamine, 6-phenyl-1,3.5-triazine-2,4-diamine] yielded the corresponding picrate salts 1–4. Theoretical studies reveal that the hydrogen-bond interaction energy decreases on increasing the steric hindrance in amines. The solid state structure of compounds 1–4 was measured by X-ray techniques and compared to the gas phase optimized geometries (DFT/B3LYP). Thermal stability of these salts has been studied by means of thermogravimetric–differential scanning calorimetry (TG–DSC) while kinetic parameters have been evaluated using models fitting and isoconversional methods. Thermolytic pathways have also been suggested.

Graphical abstractThe reaction of picric acid (2,4,6-trinitrophenol) with amines [urea, cyclohexane-1,2-diamine, 1H-1,2,4-triazole-3,5-diamine, 6-phenyl-1,3.5-triazine-2,4-diamine] yielded the corresponding picrate salts 1–4. Theoretical studies reveal that the hydrogen-bond interaction energy decreases on increasing the steric hindrance in amines. The solid state structure of compounds 1–4 was measured by X-ray techniques and compared to the gas phase optimized geometries (DFT/B3LYP). Thermal stability of these salts has been studied.Figure optionsDownload full-size imageDownload as PowerPoint slideHighlights► Synthesis of four new salts of picric acid with amines. ► Comparison of solid state and gaseous phase structure for picrate salts. ► The mechanism of thermal decomposition was studied. ► Study of the explosive behavior.