Liquid-liquid equilibria of aqueous acetic acid derivatives with trioctylamine and select organic diluents

Liquid-liquid equilibria for aqueous solutions of acetic acid derivatives, formic, monochloroacetic, dichloroacetic, and trichloroacetic acids, with trioctylamine in various diluents, 1-octanol, chloroform, hexane, and tetrachloromethane, were determined at 298 K. The loading of trioctylamine was calculated, and the extraction behavior was discussed on the basis of the loading. The degrees of extraction of these medium-strong carboxylic acids with trioctylamine are in the order 1-octanol chloroform greater than or equal to tetrachloromethane > hexane at Z(exp) < 1. The strong acid provides a larger loading of trioctylamine than the weak acid; that is, the consequence is that trichloroacetic acid > dichloroacetic acid > monochloroacetic acid > formic acid > acetic acid, and this result depends on both the acidity and hydrophobicity of the acid.