Determination of physicochemical properties of tetrabromobisphenol A

Aqueous solubility (S_w), 1-octanol/water partition coefficient (K_ow), and vapor pressure of the nonionic form of 2,2′,6,6′-tetrabromo-4,4′-isopropylidenediphenol (tetrabromobisphenol A or TBBP-A) were measured. From this, enthalpies of solution and vaporization were estimated. Furthermore, enthalpy of fusion and melting point were measured to estimate subcooled liquid vapor pressure, the infinite dilution activity coefficient, and Henry's law constant. Since TBBP-A is expected to exit in both ionic and nonionic forms at near neutral pH, pH effects on physicochemical properties were also examined. Because of the ionization of TBBP-A, S_w increased by five orders of magnitude, while K_ow decreased by eight orders of magnitude. Furthermore, an analytical model based on mass balance and dissociation of TBBP-A was applied to represent the pH dependence.