Experimental and computational study of the molecular energetics of the monoiodoanisole isomers

Abstract

The standard (p°=0.1MPa) molar enthalpies of formation, in the condensed phase, of the three monoiodoanisoles, were derived from the respective enthalpies of combustion, measured by rotating-bomb combustion calorimetry. Their enthalpies of sublimation/vaporization, at T=298.15K, were obtained by Calvet microcalorimetry using the high-temperature vacuum sublimation technique. Moreover the standard molar enthalpy, entropy and Gibbs energy of sublimation, at T=298.15K, of 4-iodoanisole were derived from the Knudsen mass-loss effusion technique.Combining the former sets of experimental results, the standard molar enthalpies of formation in the gas-phase, at T=298.15K, of 2-, 3- and 4-iodoanisole were derived, respectively, as: (15.1±2.1) kJ·mol−1; (11.8±2.2) kJ·mol−1, and (12.4±1.6) kJ·mol−1.The experimental values of the gas-phase enthalpies of formation of each iodoanisole were also estimated by means of the empirical scheme developed by Cox and by density functional theory calculations employing the B3LYP/6-311++G(d,p) approach. Estimated values are in excellent agreement with the reported experimental ones derived in the present paper.