Standard molar enthalpy of sublimation of form I nicotinamide

The standard (p degrees = 0.1 MPa) molar enthalpy of sublimation of form I nicotinamide (NIC, cr I), at 298.15 K, was determined by drop-sublimation Calvet microcalorimetry. Experiments carried out under isothermal and non-isothermal conditions led to Delta H-sub(m)degrees(NIC, cr I) = 108.0 +/- 0.5 kJ center dot mol(-1). The present study allowed to resolve to a significant extent the large discrepancy observed between published Delta H-sub(m)degrees(NIC) results obtained by calorimetry and by vapor-pressure measurements, using samples of unspecified crystal form.

Automated summary

The standard (p degrees = 0.1 MPa) molar enthalpy of sublimation of form I nicotinamide (NIC, cr I) at 298.15 K was determined using drop-sublimation Calvet microcalorimetry. The obtained result, Delta H-sub(m) degrees(NIC, cr I) = 108.0 +/- 0.5 kJ.mol(-1), significantly resolves the discrepancy between the published Delta H-sub(m) degrees(NIC) results obtained by calorimetry and vapor-pressure measurements with unspecified crystal form samples.