Novel phosphonamides, process for producing the same, and use thereof

An agent for extracting a rare earth metal ion, comprising the phosphonamide compound represented by the general formula [1]

• (wherein R1 represents an alkyl group, a cycloalkyl group, an alkenyl group, a cycloalkenyl group, an alkynyl group, an aryl group, an aralkyl group, or a heterocyclic group, with the proviso that each group may have a substituent;
• R2 represents a hydrogen atom, an alkyl group, a cycloalkyl group, an alkenyl group, a cycloalkenyl group, an aryl group, an aralkyl group, or a heterocyclic group, with the proviso that each group may have a substituent;
• R3 represents a hydrogen atom, an alkyl group, a cycloalkyl group, an alkenyl group, a cycloalkenyl group, an aryl group, an aralkyl group, or a heterocyclic group, with the proviso that each group may have a substituent;
• and the two R3s may be united to form an alkylene group, a cycloalkylene group or an arylene group).

A process for extracting a rare earth metal ion from an aqueous solution containing a rare earth metal ion, characterized by using as an extraction agent the phosphonamide compound represented by the general formula [1]

• (wherein R1 represents an alkyl group, a cycloalkyl group, an alkenyl group, a cycloalkenyl group, an alkynyl group, an aryl group, an aralkyl group, or a heterocyclic group, with the proviso that each group may have a substituent;
• R2 represents a hydrogen atom, an alkyl group, a cycloalkyl group, an alkenyl group, a cycloalkenyl group, an aryl group, an aralkyl group, or a heterocyclic group, with the proviso that each group may have a substituent;
• R3 represents a hydrogen atom, an alkyl group, a cycloalkyl group, an alkenyl group, a cycloalkenyl group, an aryl group, an aralkyl group, or a heterocyclic group, with the proviso that each group may have a substituent;
• and the two R3s may be united to form an alkylene group, a cycloalkylene group or an arylene group).