In this work

the group contribution method of Chickos et al. was applied to estimate the fusion enthalpy of isonicotinic acid

and the obtained result (29.2 kJ·mol

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) showed a large difference with the value (135 kJ·mol

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) as reported from literatures and as determined by differential scanning calorimetry (DSC). The results of DSC/TG measurement showed that the phase transition of isonicotinic acid from 187.27℃ to 277.47℃ underwent a sublimation process

with a sublimation enthalpy of 128.03 kJ·mol

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. An efficient analytical technique combining pyrolysis and gas chromatography/mass spectrometry (Py-GC/MS) was used to prove this conclusion.