Enthalpies of formation of 2,4,6-tribromophenol and of 2,4,6-tribromoaniline

Abstract

The standard ( p o = 101.325 kPa) molar enthalpies of formation at 298.15 K of crystalline 2,4,6-tribromophenol and of 2,4,6-tribromoaniline were determined by both solution-reaction calorimetry and by rotating-bomb calorimetry. The values from the two methods agreed to within the limits of experimental error. The standard molar enthalpies of sublimation at 298.15 K were measured by microcalorimetry. Δ f H m o(cr)/(kJ·mol −1 ) Δ cr g H m o/(kJ·mol −1 ) 2,4,6-Tribromophenol −98.5±2.3 97.6±1.1 2,4,6-Tribromoaniline 57.9±2.4 101.1±1.1 The derived standard molar enthalpies of formation of the gaseous compounds were compared with values estimated assuming that each group, when substituted into the benzene ring, produces a characteristic increment in the enthalpy of formation.