Computational Study of Picric Acid and Potassium Picrate

Abstract

ABSTRACT The density functional theory (DFT) method at the B3LYP/6-311 + g** level was used for predicting the structures, natural bond orbital (NBO) atomic charges, thermodynamic properties, and IR spectroscopy of picric acid (PA) and potassium picrate (PP). The IR spectroscopies were assigned. The C–NO2 bond is generally lengthier than all the other covalent bonds in both PA and PP, indicating that this bond is the weakest and prone to rupture in the decomposition process. The carbon atom that connects with oxygen atom in PP carries larger positive charges, and nitro oxygen atoms carry larger negative charges than the corresponding atoms in PA. The C–C populations of PP are more unevenly distributed than those of PA, indicating that the benzene ring of the former is less conjugated. Some C–C bonds in PP are much weaker. This weak C–C bond could be ruptured at the same time as the C–N bond in the initial decomposition process.