Thermodynamic properties of isomeric iso-butoxybenzoic acids: Experimental and theoretical study

• Vapor pressures of butoxy benzoic acid derivatives were measured.
• Vaporization, sublimation and fusion enthalpies were derived.
• Molar enthalpies of formation were measured by calorimetry.
• Thermochemical data tested for consistency using additivity rules and computations.
• Simple additivity method suggested for prediction thermochemical properties.

Standard (p° = 0.1 MPa) molar enthalpies of formation at the temperature T = 298.15 K of the 2-, 3-, and 4-iso-butoxybenzoic acids were measured using the combustion calorimetry. Standard molar enthalpies of vaporization and sublimation were derived from the vapor pressure temperature dependencies measured by the transpiration method. Molar enthalpies of the solid state phase transitions were measured by the DSC. Thermodynamic data on alkoxy substituted benzoic acids available in the literature were collected and combined with own experimental results. This data set on alkoxybenzoic acids was evaluated by using quantum-chemical and group-additivity methods.