The critical micelle concentration (CMC) of dodecyl ammonium halides and the degree of dissociation of the micelle (α) of dodecylammonium chloride were determined as functions of the concentrations of the organic additives by measuring the conductivity and the emf of the following cell: calomel/1 M-KCl/sample solution/AgCl, Ag. The CMC was raised more in the presence of acetone and dioxane than in that of acetamide, formamide, urea, and methanol, and was diminished by adding alcohols (C2–C4). The effect of the alcohols on CMC decreased in the order of the diminished hydration of the counterion, acetone and dioxane were considered to affect the dodecylammonium iodide solution specifically. The dissociation of the micelle was enhanced in the presence of organic additives. Further, we estimated the solubilized amount of the additives from the degree of dissociation of the micelle and attempted to make quantitative estimation of the increment of CMC produced by organic additives.
The Chemical Society of Japan