Thermochemical investigations of nitroresorcinols and relevant metal salts

Abstract

The standard enthalpies of formation of 2,4-dihydroxy-1.3.5-trinitrobenzene (styphnic acid), 2,4-dihydroxy-3.5-dinitrobenzene (4,6-DNR), 2,4-dihydroxy-l,5-dinitrobenzene (2,4-DNR), 2,6-dinitrotoluene (two crystal forms) have been determined by oxygen static bomb calorimetry. An isoperibol solution reaction calorimeter has been constructed. By the determination of various enthalpies of reaction and solution, the enthalpies of formation of various synthesised polymorphs of lead styphnate, lead 2,4-dinitroresorcinol, and lead 4,6-dinitroresorcinol, thallous styphnate and barium styphnate were found. From these data, enthalpies of decomposition were calculated. By use of a group additivity scheme for solids, the enthalpies of formation for a further five lead polynitroresorcinols was determined. The integral enthalpy of solution for lead nitrate was determined. A differential enthalpy of solution for lead nitrate was determined and an activity correction applied. The enthalpy of transition between the two crystal forms of2.6-dinitrotoluene was determined and heat capacities of the respective forms in the solid and liquid phase measured. Powder X-ray crystallographic study of the two forms was made.