EXTRACTION OF CARBOXYLIC-ACIDS WITH AMINE EXTRACTANTS .2. CHEMICAL INTERACTIONS AND INTERPRETATION OF DATA

The results of the mass action law analysis of part 1 are combined with the results from spectroscopic studies to analyze chemical interactions involved in the complexation of carboxylic acids with amine extractants in various diluents. Infrared spectroscopic studies were performed on anhydrous solutions of succinic, maleic, and fumaric acids to compare the effect of rigidity and configuration on complex stoichiometry. Dicarboxylic acids that form intramolecular hydrogen bonds are inhibited from forming (1,2) and (2,2) complexes. (The notation (p,q) denotes p, the number of acid molecules, and q, the number of amine molecules, in the complex.) The results from the mass action law analysis and spectroscopic studies of previous investigators indicate that formation of the (1,1) complex involves ion-pair or hydrogen-bond formation between the acid and the amine, while (2,1) complex formation involves hydrogen bonding between the carboxyl of the second acid and the carboxylate of the first. The effects of acid and diluent on the magnitude of the (1,1) equilibrium constant are discussed. © 1990, American Chemical Society. All rights reserved.