Crystal structure and thermochemical properties of n-octanammonium oxalate (C8H17NH3)2C2O4(s)

Abstract: A novel compound n-octanammonium oxalate (C8H17NH3)2C2O4(s) was synthesized by the method of liquid phase reaction. Crystal structure of n-octanammonium oxalate was determined by X-ray crystallography. The lattice potential energy of the compound was calculated to be U POT =1050.90kJ·mol−1. Molar enthalpies of dissolution of the compound at different concentrations m/(mol·kg−1) were measured by an isoperibol solution–reaction calorimeter at T =298.15K. According to the Pitzer’s electrolyte solution theory, the molar enthalpy of dissolution of the compound at infinite dilution () and Pitzer parameters () were obtained. The values of apparent relative molar enthalpies (ΦL ) of the title compound and relative partial molar enthalpies of the solute and the solvent at different concentrations were derived from experimental values of enthalpies of dissolution. The enthalpy change of the synthesis reaction of n-octanammonium oxalate was determined to be by an isoperibol solution–reaction calorimeter, and standard molar enthalpy of formation of (C8H17NH3)2C2O4(s) was calculated to be by using the enthalpies of dissolution and other auxiliary thermodynamic quantities. [Copyright &y& Elsevier]