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Thermochemistry of 4-HOC 6 H 4 COR (R = H, CH 3 , C 2 H 5 , n- C 3 H 7 , n -C 4 H 9 , n -C 5 H 11 , and n -C 6 H 13 ) compounds

2016; Elsevier BV; Volume: 104; Linguagem: Inglês

10.1016/j.jct.2016.09.026

1096-3626

Cátia S. D. Lopes, Filipe Agapito, Carlos E. S. Bernardes, Manuel E. Minas da Piedade,

Thermodynamic properties of mixtures

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° = 1 bar) molar enthalpies of formation in the solid, ΔfHmo(cr), and gaseous, ΔfHmo(g), states, at T = 298.15 K, could be derived for the complete series of compounds. An excellent linear correlation was found when the ΔfHmo(g) values were plotted as a function of the number of carbon atoms in the alkyl side chain (nc), 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 nc was also noted, the CH2 increment being 6.6 ± 0.6 kJ·mol−1.