Thermodynamics of mixtures with strongly negative deviations from Raoult'sLaw - Part 4. Application of the DISQUAC model to mixtures of 1-alkanols with primary or secondary linear amines. Comparison with Dortmund UNIFAC andERAS results

Binary mixtures of l-alkanols with primary or secondary linear amines have been characterized in the framework of DISQUAC, The interaction parameters for the corresponding OH/NH2, and OH/NH contacts are reported. DISQUAC repr esents fairly well the thermodynamic properties examined, which are critica lly evaluated: vapor-liquid equilibria (VLE), molar excess Gibbs energies ( GE) and molar excess enthalpies (HE). For example, polyazeotropy of the met hanol + diethylamine mixture is well reproduced. The methanol + ammonia sys tem can be treated similarly to other l-alkanols + primary amine systems (i .e., ammonia is assumed, as in a previous work, to be a primary amine witho ut C atoms). The results are discussed in terms of effective dipole moments . The information derived from the concentration-concentration structure fa ctors is briefly analyzed. DISQUAC provides better results than the Dortmun d version of UNIFAC using the published geometrical and interaction paramet ers. Particularly, DISQUAC improves results on GE and for systems containin g methanol, DISQUAC results on HE are also compared to those obtained from the ERAS model. For systems containing primary amines, parameters available in literature were used along calculations. In the case of methanol + diet hylamine and 1-alkanols + dibutylamine mixtures, new ERAS parameters are re ported in this work. The mean standard deviations for HE Obtained using DIS QUAC and ERAS, are 151 and 216 J mol(-1), respectively. DISQUAC also improv es results on GE, while ERAS describes properly the available excess volume (VE) data. (C) 2000 Elsevier Science B.V. All rights reserved.