title: Phase equilibria and thermodynamics of p-hydroxybenzoic acid.
abstract: The prevalence of phases and associated solubilities of p-hydroxybenzoic acid have been investigated in methanol, acetonitrile, acetic acid, acetone, water, and ethyl acetate at temperatures from 10 to 50 degrees C. Thermodynamic data was acquired through determination of van't Hoff enthalpy of solution, enthalpy of fusion, and melting temperature. Indications of polymorphic enantiotropy were found primarily through solubility analysis and FTIR-ATR. A comprehensive thermodynamic investigation disclosed correlation between the van't Hoff enthalpy of solution and the solubility in different solvents. A higher solubility is linked to a lower van't Hoff enthalpy of solution. A thermodynamic analysis to discriminate between different solid phases is presented.
authors.affiliation: Department of Chemical Engineering and Technology, Royal Institute of Technology, SE-100 44 Stockholm, Sweden.
authors.forename: Fredrik L
authors.initials: FL
authors.lastname: Nordström
authors.forename: Ake C
authors.initials: AC
authors.lastname: Rasmuson
mesh_terms: D000085:Acetates / Q000737:chemistry; D019342:Acetic Acid / Q000737:chemistry; D000096:Acetone / Q000737:chemistry; D000097:Acetonitriles / Q000737:chemistry; D003460:Crystallization; D000432:Methanol / Q000737:chemistry; D010226:Parabens / Q000737:chemistry*; D044367:Phase Transition; D012995:Solubility; D012997:Solvents / Q000737:chemistry; D013816:Thermodynamics; D044366:Transition Temperature; D014867:Water / Q000737:chemistry
chemical_list: D000085:Acetates; D000097:Acetonitriles; D010226:Parabens; D012997:Solvents; D014867:Water; D000096:Acetone; C007650:ethyl acetate; C038193:4-hydroxybenzoic acid; D019342:Acetic Acid; D000432:Methanol; C032159:acetonitrile