Thermochemistry of substituted thiophenecarbonitrile derivatives

The standard (p∘ = 0.1 MPa) molar energies of combustion in oxygen of 2-thiophenecarbonitrile, 3-thiophenecarbonitrile, 2-thiopheneacetonitrile, 3-thiopheneacetonitrile, and 3-methyl-2-thiophenecarbonitrile were measured, at T = 298.15 K, by rotating-bomb calorimetry. The standard molar enthalpies of vaporization of these compounds at T = 298.15 K were determined using high temperature Calvet microcalorimetry. These values were used to derive the standard molar enthalpies of formation of the title compounds in their crystalline and gaseous phases, respectively. Compounds-ΔcUm∘(l)/(kJ · mol−1)-ΔfHm∘(l)/(kJ · mol−1)ΔlgHm∘/(kJ · mol−1)2-Thiophenecarbonitrile3192.4 ± 1.4198.5 ± 1.649.5 ± 1.13-Thiophenecarbonitrile3190.9 ± 1.3197.0 ± 1.451.6 ± 1.92-Thiopheneacetonitrile3839.6 ± 1.6167.6 ± 1.860.5 ± 1.33-Thiopheneacetonitrile3838.8 ± 1.7166.7 ± 1.861.1 ± 1.33-Methyl-2-thiophenecarbonitrile3829.6 ± 1.6157.6 ± 1.754.4 ± 1.2Full-size tableTable optionsView in workspaceDownload as CSVThe standard molar enthalpies of formation for the title compounds in the gaseous state were derived and the results are interpreted in terms of structural effects.