Atmosphere/water partition of halocyclohexanes from vapour pressure and solubility data

Original values of the atmosphere/water partition coefficients of chlorocyclohexane and bromocyclohexane are reported at temperatures between 0 and 40 °C. These values could be obtained from the Henry's law constants calculated from aqueous solubility and vapour pressure data for the two solutes. Both properties were measured in this work and are reported in the temperature ranges 1 to 40 °C and −10 to 100 °C, respectively. Chlorocyclohexane is more volatile and more soluble in water than bromocyclohexane. At 25 °C, chlorocyclohexane has a vapour pressure of 1077.7 kPa and a mole fraction aqueous solubility of 3.22×10−5. Bromocyclohexane has a vapour pressure of 409.5 Pa and a mole fraction solubility of 0.781×10−5 at the same temperature. These values lead to atmosphere/water partition coefficients of 24.4 and 38.2 for chlorocyclohexane and bromocyclohexane, respectively. A simple group contribution scheme is presented that makes use of the present values and of literature data to allow the prediction of Henry's law constants, with reasonable accuracy, of halogenated-substituted organic compounds at 25 °C.