Studies of divalent metal soaps

• Main Author: Seddon, A. B.
• Published: University of Huddersfield 1984
• Subjects: 541; Physical chemistry
• Online Access: http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.351381

This thesis contributes towards work whose long term aim is to comprehensively study organic solutions of metallic soaps. The thesis begins with an introduction in which the aggregation behaviour of heavy metal soaps in nonaqueous media is compared and contrasted with the behaviour of alkali metal soaps in an aqueous medium. Gravimetry and atomic absorption spectrophotometry are employed to measure the solubility of the zinc and copper II n-alkanoates in a number of organic solvents. In most cases the solubility is seen to rise sharply when a critical solution temperature (eST) is reached. VPO studies of copper soap solutions indicate the presence of aggregates of low aggregation number at concentrations close to the concentration at the eST, and above this concentration the aggregation number increases over a wide concentration range. It is concluded that the solutions do not show Krafft behaviour and it is proposed that formation of a lyotropic liquid crystalline soap phase is responsible for the eST behaviour. Up to 4000-fold solubility enhancements of copper II n-alkanoates in binary hydrocarbon/alcohol solvent systems are observed. Where the alcohol is of low chainlength, however, a secondary process causes massive reprecipitation with time; it is proposed that soap/alcohol complex formation is ultimately responsible. VPO studies show that copper alkanoates do not aggregate in pyridine; their high solubility in pyridine is due to complex formation in solution. A wide survey of complex formation by metal soaps has been undertaken using the technique of TGA. TGA shows that alkali and alkaline earth metal soaps can complex with parent acid. Chromium III n-alkanoates are observed to complex with parent acid, long chain alcohols and &mines but not esters. copper 11 soaps are shown to form isolatable pyridine co-ordinate complexes. The copper 11 dodecanoate dipyridine complex has not been previously reported. TGA indicates that copper soaps may also complex with long chain amines. It is concluded that future solution studies of these metal soap complexes will prove interesting.