Nicotinamides: Evaluation of thermochemical experimental properties

• Vapor pressures measured by transpiration method.
• Enthalpies of solution measured using high-precision solution calorimetry.
• Enthalpies of fusion measured by DSC.
• Sublimation enthalpies derived from transpiration and solution calorimetry in agreement.
• Experimental results evaluated and compared with G4 calculations.

Vapor pressures of the isomeric 2-, 3-, and 4-pyridinecarboxamides were measured by using the transpiration method. The enthalpies of sublimation/vaporization of these compounds at 298.15 K were derived from vapor pressure temperature dependences. The enthalpies of solution of the isomeric pyridinecarboxamides were measured with the high-precision solution calorimetry. The enthalpies of sublimation of 3- and 4-pyridinecarboxamides were independently derived with help of the solution calorimetry based procedure. The enthalpies of fusion of the pyridinecarboxamides were measured by the DSC. Thermochemical data isomeric pyridinecarboxamides were collected, evaluated, and tested for internal consistency. The high-level G4 quantum-chemical method was used for mutual validation of the experimental and theoretical gas phase enthalpies of formation successfully.