Some properties of sulfoacetic acid and 3-sulfopropionic acid and their use as analytical masking agents

The values of K~ for sulfoacetic and 3-sulfop:i:'oBionic acids were determined potentiometrically. The values are (8.6 t 0.3) x 10-~ and (3.0 t O.l) x lo-5, respectively. These values or Ka2 were much lower. than those predicted by the Branch and Calvin equation for the calculation of values or pKa of derivf.tives of acetic acid. The presence of intramolecular hydrogen bonds in sulfoacetate and 3sulfopropionate accounted for some of the discrepancy between the calculated and observed values of Ka2 for sulfoacetate and 3-sulfopropionate. A proposition was made that the assumption of single bond~character far the sulfur-o~gen bond in the Branch and Calvin treatment yields high .results for tm values of ~ or acids with substituted sulfonate groups. It wa~ suggested that the sulfonate group be classified as a resonating group for the Branch and Calvin treatment, and that it be given an inductive constant as a unit. The water solubility of acetate at pH 5.0 was found to be much greater than sulfoacetate or 3-sulfopropionate at this pH. At any given concentration, acetate was found to be a more effective masking agent for thorium than either sulfoacetate or 3-sulfopropionate. The three masking agents in the order of their decreasing masking efficiencies are, acetate) 3-sulfopropionate) sulfoacetate. A method for the determination of trace amourits of aluminum in thorium was developed using Enta and 3-sulfopriopionate to mask the thorium. Aluminum was extracted from aqueous thorium solutions with a 0.5 per cent solution of 8-quinolinol in chloroform. The aluminum was determined spectrophotometrically as the tris(8-quinolinolo)aluminum(III) complex. * This report is based on an M.S. thesis by Joseph Zimmerman submitted June, 1956, to Iowa State College, Ames, Iowa. This work was done under contract with the Atomic Energy Commission.