Standard molar enthalpy of formation of vanillin

Abstract

Specific energy of combustion of vanillin was determined using the bomb calorimeter BIC 100 with high degree of thermal protection from environment impact. The standard deviation of mean for energy equivalent was 0.01%. Based on the specific energy of combustion −(25,072.1 ± 7.4) J g−1, the standard molar enthalpy of combustion and standard molar enthalpy of formation for vanillin in the crystalline state at 298.15 K were calculated to be −(3815.9 ± 1.1) and −(475.5 ± 1.5) kJ mol−1, respectively. Standard molar enthalpy of formation of vanillin in the gaseous state was determined to be −(375.8 ± 2.1) kJ mol−1 from ab initio calculations using density functional theory and G3 methods. The enthalpy of sublimation of vanillin at 298.15 K, determined as difference between standard molar enthalpies of formation of vanillin in crystalline and gaseous states, was found to be 100 ± 3 kJ mol−1.