Double decomposition reactions are studied through the screening of crude oleic soaps and inorganic compounds. Our study agrees with the exchange theory formulated for pure soaps: reactions proceed in the direction of the formation of the most insoluble compound under salting-out conditions. By studies on exchange reactions between lithium soap and calcium chloride, we define a domain of LiOOCR/CaCl2/H2O mixtures in which conversion of the lithium soap into the calcium one is highest: under stoichiometric conditions (LiOOCR/CaCl2 = 2/1), calcium chloride should be dilute ([NaCl2] = 11-19 g/L), and under conditions of excess calcium chloride (LiOOCR/CaCl2 = 2/4.9), it can be less dilute ([CaCl2] = 53 g/L). Kinetic studies indicate that the yield of the LiOOCR/CaCl2 exchange reaction is highest for reactions carried at 90 degreesC for 3 h. These reactions kinetics can be enhanced by adding ethanol to the aqueous medium (50 wt % at 50 degreesC and 25 wt % at 90 degreesC).