Calorimetric and computational study of (1H-Indol-n-yl)methanol and 2-(1H-Indol-n-yl)ethanol (n=2, 3)

Abstract In the present work, the gas-phase standard molar enthalpy of formation of 2-(1H-indol-3-yl)ethanol was derived, at T  = 298.15 K, from the enthalpy of combustion for the crystalline compound, measured by static-bomb calorimetry, and its enthalpy of sublimation obtained from Calvet microcalorimetry measurements. The standard molar enthalpies of formation of this compound and for (1H-indol-2-yl)methanol, (1H-indol-3-yl)methanol and 2-(1H-indol-2-yl)ethanol were calculated using the composite G3 method. The experimental value of the gas-phase enthalpy of formation of 2-(1H-indol-3-yl)ethanol is ‒(48.5 ± 3.3) kJ mol −1 , being in excellent agreement with the G3 value, thus giving confidence to the estimates. The results were analysed in terms of the enthalpic methylene increments and compared with other related systems.