Solvent extraction of actinides and lanthanides by CMP(O)- and N-acyl(thio)urea-tetrafunctionalized cavitands:: Strong synergistic effect of cobalt bis(dicarbollide) ions

The synthesis of two carbamoylmethylphosphate (CMP)-and-phosphine oxide (CMPO)-tetrafunctionalized cavitands with a propyl spacer between the cavitand platform and the chelating sites is described. Liquid-liquid extractions with CMP(O)- and N- acyl( thio)urea-tetrafunctionalized cavitands were performed from aqueous nitric acid into dichloromethane or o-nitrophenyl hexyl ether ( NPHE). The extraction of americium (III) and europium ( III) from aqueous nitric acid into NPHE was studied in both the absence and presence of Br-6-COSAN as a synergist. CMP(O) cavitands are more efficient extractants than the corresponding N-acyl(thio) urea derivatives, whereas the latter ones show an interesting selectivity for americium (III) over europium (III) in the presence of Br6-COSAN. The introduction of a propyl chain between the cavitand platform and the chelating groups increases the