Phase behavior of tetrabutylammonium salt in aromatic hydrocarbons or aqueous solutions

The solubility of tetrabutylammonium salt (TBAX; X = Cl, Br, or I) in benze ne was examined as a function of temperature. The solubility curve had spec ific features, which were characterized by critical values corresponding to the Krafft point and the critical micelle concentration of ionic surfactan ts in water. Above the critical concentration, TBAX was assumed to aggregat e in benzene, based on NMR analyses. A slight difference of the oil structu re exerted a significant effect on the solubility behavior. In the presence of sodium halides, TBACl or TBABr with water exhibited a specific temperat ure that was similar to the cloud point. Above that temperature, TBAX was l iberated as a liquid to form a liquid-liquid two-phase. The solubility of T BAI in water was poor. It gave a liquid-solid two-phase at low temperatures or a liquid-liquid two-phase above 69 degreesC, unless the TBAI concentrat ion was too low. The solubility of TBAX in aqueous solution was also depend ent on the metal cation of the inorganic salts.