| Abstract |
The thermochemistry of 4-HOC6H4COR (R = H, CH3, C2H5, n-C3H7, n-C4H9, n-C5H11, and n-C6H13) compounds was investigated using enthalpy of vaporization/sublimation measurements by Calvet-drop microcalorimetry and W1-F12 and CCSD(T)-F12 ab initio calculations. Based on the obtained results, standard (p degrees = 1 bar) molar enthalpies of formation in the solid, Delta H-f(m)degrees(cr), and gaseous, Delta H-f(m)degrees(g), states, at T = 298.15 K, could be derived for the complete series of compounds. An excellent linear correlation was found when the Delta H-f(m)degrees(g) values were plotted as a function of the number of carbon atoms in the alkyl side chain (n(c)), with a CH2 increment of 21.8 +/- 0.2 kJ.mol (1). Despite the differences in molecular packing between the crystalline 4-HOC6H4COR compounds, approximate additivity of their cohesive energies (as measured by the standard molar enthalpy of sublimation) with n(c) was also noted, the CH2 increment being 6.6 +/- 0.6 kJ.mol (1). (C) 2016 Elsevier Ltd. |
