Metal chelate exchange in the organic phase-I Theory: application in spectrophotometry and complex chemistry

Metal chelates, extracted from an aqueous phase by organic solvents, can react with other chelating agents (or their metal chelates) dissolved in the same solvent. This exchange of metal chelates in the organic phase can be used for (1) investigation of the exchange equilibrium and composition of the metal chelates formed, (2) determination of the extraction constants, (3) preparation of new inner-complexes soluble in organic solvents, and (4) spectrophotometric determination of small amounts of metals. The theory and experimental verification of this phenomenon are given. The extraction constants of silver and zinc diethyldithiocarbamates in carbon tetrachloride have been determined by means of the extraction constants of the corresponding dithizonates. A mixed complex of arsenic(III) with dithizone and diethyldithiocarbamic acid has been prepared and its properties studied. A simple method for spectrophotometric determination of microgram quantities of arsenic is proposed.