Standard molar enthalpies of formation of some vinylfuran derivatives

Abstract

The standard ( p ∘ = 0.1 MPa) molar enthalpies of combustion, Δ c H m ∘ , for crystalline 2-furanacrylic acid, 3-furanacrylic acid, and 3-(2-furyl)-2-propenal and for the liquid 2-furanacrylonitrile were determined, at the temperature 298.15 K, using a static bomb combustion calorimeter. For these compounds, the standard molar enthalpies of phase transition, Δ cr,l g H m ∘ , at T = 298.15 K, were determined by Calvet microcalorimetry. For the two crystalline furanacrylic acids the vapour pressures as function of temperature were measured by the Knudsen effusion technique and the standard molar enthalpies of sublimation, Δ cr g H m ∘ , at T = 298.15 K were derived by the Clausius–Clapeyron equation. The results are as follows: - Δ c H m ∘ ( cr,l ) / ( kJ · mol - 1 ) Δ cr,l g H m ∘ / ( kJ · mol - 1 ) Calvet Knudsen 2-Furanacrylic acid (cr) 3149.8 ± 0.5 103.0 ± 0.7 103.3 ± 0.5 3-Furanacrylic acid (cr) 3151.5 ± 0.7 104.9 ± 1.1 106.8 ± 0.5 3-(2-Furyl)-2-propenal (cr) 3425.7 ± 1.2 82.3 ± 0.4 2-Furanacrylonitrile (l) 3562.5 ± 1.3 65.2 ± 0.6 These values were used to derive the standard molar enthalpies of formation of the compounds in their condensed and gaseous phases, respectively. For 2-furanacrylic acid and 3-furanacrylic acid, the standard ( p ∘ = 0.1 MPa) molar enthalpies, entropies, and Gibbs functions of sublimation, at T = 298.15 K, were derived. The derived standard molar enthalpies of formation in the gaseous state are analysed in terms of structural enthalpic increments.