The standard (p0=0.1
MPa) molar enthalpies of formation, in the condensed phase, of nine linear-alkyl
substituted thiophenes, six in position 2- and three in position 3-, at T=298.15 K, were derived from the standard massic
energies of combustion, in oxygen, to yield CO2(g)
measured by rotating-bomb combustion calorimetry. The standard molar enthalpies
of vaporization of these compounds were measured by high temperature Calvet
Microcalorimetry, so their standard molar enthalpies of formation, in the
gaseous phase, were derived.
The results are discussed in terms
of structural contributions to the energetics of the alkyl-substituted thiophenes,
and empirical correlations are suggested for the estimation of the standard
molar enthalpies of formation, at T=298.15
K, for 2- and 3-alkyl-substituted thiophenes, both in the condensed and in
the gaseous phases.