Solvent extraction of some diprotic nitroaromatic acids and of their complexes with some actinides—I: Dissociation constants and solvent extraction of 3-nitro- p-cresol-5-sulphonic acid with tributyl-phosphate

Abstract

The second dissociation constant, K 2 H= a H[A 2−]/[HA −], for 3-nitro- p-cresol-5-sulphonic acid (H 2A) in 1·0M (H, Na)Cl at 25°C has been determined by potentiometric titration and u.v.-visible spectrophotometry as (2·71 ± 0·07). 10 −7 and (2·72 ± 0·16). 10 −7, respectively. The solvent extraction of H 2A from 1M (H, Na)Cl with TBP in n-dodecane at 25°C has also been studied. The extractable species appears to be H 2A·3TBP, its apparent formation constant, K H 2 A .3 TBP=[ H 2 A·3 TBP]/a H [HA −][TBP] 3, is 2·27 ± 0·06. The value of the dissociation constan, K 1 H= a H[HA −]/[H 2A], has been calculated from the extraction data as 2·06±0·23.