An Extractant for Rare Earth Metals

N,N-Di-n-octyl-3-oxapentanedioic acid monoamide (1) is a podand host forming complexes with metal ions, which was reported by J. Beger et al. in 1990.¹⁾ By using the complex forming ability of 1, it has been able to extract rare earth metal ions such as ytterbium and lanthanum, alkaline earth metal ions such as calcium and strontium, and metal ions like copper, cobalt and zinc. Therefore, the application of 1 to minor metal recovery has been studied.^2,3)