COSMO-RS analysis on mixing properties obtained for the systems 1-butyl-X-methylpyridinium tetrafluoroborate [X = 2,3,4] and 1,ω-dibromoalkanes [ω = 1–6]

Abstract

A theoretical–experimental study for a set of 18 binary systems comprised of [bXmpy][BF₄] (X = 2–4) + 1,ω-Br(CH₂)_vBr (v = ω = 1–6) at a temperature of 298.15 K is presented. The solubility curves are determined for each binary system, establishing the intervals of measurement for the excess properties, H^E_m and V^E_m. These properties are then determined for those systems that present a miscibility zone. Binary systems containing 1,ω-dibromoalkanes with ω = 5,6 present reduced solubility intervals at the temperature of 298.15 K. However, the mixtures with 1,1-dibromomethane were totally miscible with the three isomers of 1-butyl-X-methylpyridinium tetrafluoroborate. Mixtures with dibromomethane present H^E_m < 0, whereas H^E_m > 0 for the other binary systems. Sigmoidal curves were observed for the V^E_m describing expansion and contraction processes for all the systems, except for the mixtures of [b2mpy][BF₄] with the smaller dibromoalkanes, which present contraction effects. The COSMO-RS methodology was used to estimate the solubilities and the intermolecular interaction energies, giving an acceptable explanation of the behavioral structure of pure compounds and solutions.