Physicochemical Studies on Cobalt Salts of Higher Fatty Acids. I. Preparation of Cobalt Soap by Metathesis

Abstract

Abstract As a method of preparation of cobalt soap, metathesis between alkaline soap and cobalt salt was investigated. Cobalt stearate, palmitate and myristate were obtained in pink, blue and red forms according to conditions. Cobalt laurate in blue form was not observed. Metathetic products were always pink at the beginning. If the system has a solvent ratio (solvent to water) higher than 1 : 1, and the solution after mixing is acidic, the color of soap will turn blue with stirring. It will change red later when left in the solution. The blue form could not be obtained with acetone or methanol as a solvent. The speed of the color change became considerably slower with fatty acid of a shorter chain length. In substitution reaction between stearic acid and cobalt acetate with a solvent ratio higher than 1 : 1, the same color changes were observed. But in this system the addition of some alkali suppressed markedly the color change, and at an exactly neutralized metathetic reaction the soap did not turn blue. Even in this case, when acetone was used instead of ethanol, the color change was observed, but the speed was very slow.