Energetics of hydroxytetralones: A calorimetric and computational thermochemical study

The standard (p° = 0.1 MPa) molar energies of combustion in oxygen at T = 298.15 K of 5-hydroxy- and 6-hydroxy-α-tetralone were measured by static bomb calorimetry. The values of the standard molar enthalpies of sublimation at T = 298.15 K were obtained by Calvet microcalorimetry. Combining these results, the standard molar enthalpies of formation of the compounds in the gas-phase at T = 298.15 K have been calculated: 5-hydroxy-α-tetralone -(262.5 ± 2.3) kJ · mol^-1 and 6-hydroxy-α- tetralone -(268.1 ± 2.2) kJ · mol^-1. Additionally, high-level single-point calculations based on density functional theory with the B3LYP hybrid exchange-correlation energy functional and extended basis sets as well as on two more accurate correlated computational techniques of the MCCM/3 suite have been performed for the studied compounds. The agreement between experiment and theory gives us confidence to estimate the enthalpies of formation of 7-hydroxy and 8-hydroxy-α-tetralone. Similar calculations were done for 5-, 6-, 7-, and 8-hydroxy-β-tetralone, for which experimental work was not done.