Abstract: New diphosphonic derivatives are capable of extracting the uranium in phosphoric acid with a P205 content ranging from 10 to 50 per unit.The new diphosphonic derivatives have the following formula: ##STR1## wherein R is selected from the group consisting of hydrogen and alkyl radicals having 1 to 15 carbon atoms and having at most 2 branchings in the alkyl radical, and A is a mono- or di- substituted methylene radical wherein the substituents are selected from the group consisting of an alkyl group having at most two branchings, hydroxyl, an amino group, and hydrogen, wherein the total number of carbon atoms in the R and A groups is from 15 to 50 carbon atoms, with the proviso that when A is substituted by hydroxy or amino. A has 15 to 25 carbon atoms, and wherein A is linked to a water insoluble crosslinked ion exchange resin skeleton.

Abstract: A water insoluble ion exchange resin having a crosslinked, three dimensional resin skeleton and an active group of the formula: ##STR1## wherein R is selected from the group consisting of hydrogen and an alkyl radical having 1-15 carbon atoms and having at most two branchings in the alkyl group, and A is a mono-, di-, or tri-substituted ethylene radical or mono- or di-substituted methylene radical, wherein the substituents are selected from the group consisting of an alkyl group having at most two branchings, hydroxy, an amino group and hydrogen and wherein A provides a link binding the active group to the resin skeleton.