Effect of 4-substitution on the thermodynamics of hydration of phenol and the phenoxide anion

Abstract

Enthalpies, entropies, and free energies of sublimation of phenol, 4-bromophenol, 4-formylphenol, and 4-nitrophenol have been evaluated from measurements of the vapour pressures of the solid phenols as a function of temperature. Heats of solution of the phenols in water have been determined calorimetrically and together with solubility data allow calculation of the entropies of solution. Enthalpies, free energies, and entropies of hydration are deduced and are discussed in relation to the effect of 4-substituents on the thermodynamics of ionization of phenol in water. Enthalpies of solution and solvation of the four phenols in methanol have also been measured.THE ionization of a 4-substituted phenol in water is accompanied by an entropy change which is less negative the more electron-withdrawing is the 4-substituent . l y 2 The differences between the entropies of ionization for a

Standard partial molal properties of aqueous alkylphenols and alkylanilines over a wide range of temperatures and pressures

“…Their values are in good agreement with those published by Gillet (1990) for phenol and aniline at 298 K, using the same type of calorimeter. These data were complemented by earlier determinations of Fernandez and Hepler (1959) and Parsons et al (1971Parsons et al ( , 1972) that were obtained using relatively simple instrumentation but agree reasonably well with the above data. The values of Arnett et al (1976) for phenol and three cresols have been omitted because they are systematically lower by at least 10% compared to other data.…”

“…r Estimated from Joback's group contribution scheme (Poling et al, 2001). Parsons et al (1971). e Gillet (1990).…”

“…Several values at 298 K were taken from the reviews of Shiu et al (1994) and Mackay et al (1995). The only source reporting directly D h G (298 K) determined from solubilities and vapor pressures for phenol, o-cresol and p-cresol is Parsons et al (1971Parsons et al ( , 1972. In order to increase the number of D h G data for toluidines, we have determined the Henry's law constants at three temperatures by combining the results of solubility measurements presented above with vapor pressures of pure solutes.…”

Reprint of: Crystalline and liquid vapour pressures of the four p-monohalophenols: A thermodynamic study of their phase transitions

“…Equations (19) and (20), express these correlations that are also shown in figure 10. Thermodynamic results for the vaporisation of the p-halobenzoic acids are not reported in the literature.…”

“…These results are, respectively, only 1.8 kJ Á mol À1 and 1.3 kJ Á mol À1 lower than the ones derived in this work. Vapour pressures of crystalline p-bromophenol were reported by Parsons and Rochester[19], at only three different temperatures. They are also close to the vapour pressures measured in this study, but the derived result for enthalpy…”