The standard(po = 0.1 MPa) molar enthalpies of formation for liquid 1-phenylimidazole (1PhIMI) and 1-phenylpyrazole (1PhPYR) were derived from the standard molar enthalpies of combustion, in oxygen, at T = 298.15 K, ΔcHmo, measured by static bomb combustion calorimetry. The molar heat capacities of both liquids were measured, in the temperature range (268 to 381) K, by differential scanning calorimetry. The standard molar enthalpies of vaporisation, at the temperature 298.15 K, ΔlgHmo, were measured by Calvet microcalorimetry. The derived standard molar enthalpies of formation in the gaseous state are discussed comparatively.

Thanks are due to Junta National de Investigacao Cientıfica e Tecnologica (JNICT),Lisbon, Portugal and Consejo Superior de Investigaciones Cientıficas (CSIC), Madrid, Spain, for a joint research project CSIC/JNICT. Financial support from DGICYT, Spain (PB96-0927-C02-01 and PB96-0004-C03-0103) is acknowledged. The financial support of the Praxis XXI, project 2/2.1/QUI/54/94, is acknowledged.