Steric effect of substituents on the extraction of lanthanoids(III)with N-p-(n-, iso- and tert-)butylbenzoyl-N-phenylhydroxylamine

摘要

N-p-(n-, iso- and tert-)Butylbenzoyl-N-phenylhydroxylamine (HL) was synthesized to evaluate the steric effect of the substituent on the mutual extraction separation of representative lanthanoids(III) (Ln). Lanthanoids(III) were all found to be extracted with compounds as self-adducts of the form LnL_3(HL)_2. It was found that the structure of the substituents in N-p-butylbenzoyl-substituted N-phenylhydroxylamine is closely related to the separation factor for the pair of Yb/Eu. The separation factorsfor a pair of Eu/Yb with these compounds decreased in the order of ten -butyl derivative > iso- > n-, with a decreasing Taft's E_s value, that is, with an increasing steric effect of the substituent group. The correlation between the separation factor and the stereochemical shape of the substituent was also investigated.