EFFECT OF SUBSTITUENTS AT THE NITROGEN ATOM IN DIARYL[DIALKYL(DIARYL)CARBAMOYLMETHYL]PHOSPHINE OXIDES ON THEIR EXTRACTION ABILITY AND SOLUBILITY

Extraction of nitric acid and americium(Ill) with dichloroethane solut ions of diphenyldialkyl(diaryl)carbamoylmethyl]phosphine oxides contai ning various substituents at the nitrogen atom has been studied. Compl exes with one, two, or three acid molecules per reagent molecule are e xtracted from nitric acid solutions. The extraction constants of nitri c acid (K-ex(HNO3)) with all reagents have been calculated. The K-ex(H NO3) is linearly dependent on the reagent basicity (pK(a)). Americium( III) is extracted by octyl-substituted reagents as di- and trisolvates and by other reagents as disolvates. With increasing pK(a), the extra ction constants of americium (K-ex(Am)) increase, irrespective of the nature of substituent at the nitrogen atom. In extraction of americium (III) with reagents aryl-substituted at the nitrogen atom, no anomalou s aryl strengthening (AAS) is observed. The effect of alkyl substituen ts at phosphorus and nitrogen atoms on the extraction ability of the r eagents is almost identical. The difference in this effect is revealed only in the systems with aryl-substituted reagents owing to effect of AAS.