Experimental and computational study on the molecular energetics of monobromoanisole isomers

Abstract

The standard ( p° = 0.1 MPa) molar enthalpies of formation in the liquid phase of three isomers of bromoanisole were derived from the standard molar energies of combustion, in oxygen, which yields CO 2(g) and HBr · 600H 2O(l), at T = 298.15 K, measured by rotating bomb combustion calorimetry. The determination of the standard molar enthalpies of vaporization of these compounds, at T = 298.15 K, was done by Calvet microcalorimetry using the high-temperature vacuum sublimation technique. Combining the former sets of experimental results, the standard molar enthalpies of formation, in the gas-phase, were derived. The gas-phase enthalpies of formation were also estimated by means of the empirical scheme developed by Cox and by density functional theory calculations performed at the B3LYP/6-31+G(d) level of theory. - Δ c U m ∘ ( l ) / ( kJ · mol - 1 ) - Δ f H m ∘ ( l ) / ( kJ · mol - 1 ) Δ l g H m ∘ / ( kJ · mol - 1 ) 2-Bromoanisole 3629.0 ± 1.4 101.5 ± 1.7 61.8 ± 1.3 3-Bromoanisole 3624.0 ± 1.4 106.5 ± 1.7 58.0 ± 1.2 4-Bromoanisole 3623.8 ± 1.5 106.7 ± 1.8 58.3 ± 1.2