EXCESS-ENTHALPIES OF BINARY-MIXTURES CONTAINING ALPHA,OMEGA-DIBROMOALKANES - MEASUREMENT AND ANALYSIS IN TERMS OF GROUP CONTRIBUTIONS (DISQUAC)

Excess enthalpies at 298.15 K and atmospheric pressure are reported for binary liquid mixtures of 1,3-dibromopropane, 1,4-dibromobutane, 1,5-dibromopentane, 1,6-dibromohexane and 1,8-dibromooctane + cyclohexane. These experimental results, along with our previous ones, as well as literature data, on liquid-vapor equilibria (excess Gibbs energies) and excess enthalpies of alpha,omega-dibromoalkane + n-alkanes, are interpreted in terms of the DISQUAC group contribution model. The systems are characterized by three types of contact surfaces: bromine, n-alkane and cyclohexane. The dispersive interaction parameters are smaller for cyclohexane than for n-alkane and are independent of the mutual separation of the bromine atoms in the alpha,omega-dibromoalkane. The quasichemical parameters are the same for n-alkanes and cyclohexane and increase regularly with increasing separation of the two bromine atoms in the molecule (proximity effect) reaching, for 1,5-dibromopentane and longer alpha,omega-dibromoalkanes, the constant value of 1-bromoalkanes.