Selective extraction of perrehnate anion in nitric acid solution using 2,2′-(methylimino)bis(N,N′-diethylacetamide) as an extractant

In order to examine extraction behavior of ReO4− from HNO3 aqueous solution to dichloromethane containing 2,2′-(methylimino)bis(N,N-diethylacetamide) (MIDEA) as an extractant, we have measured distribution ratios (D) by changing [HNO3] under constant [MIDEA] (1.064 × 10−1 M, M = mol dm−3) in CH2Cl2 and also by changing [MIDEA] in CH2Cl2 under constant [HNO3] (0.1 M) and (0.2 M). As a result, it was found that the D values decrease with an increase in [HNO3] and increase with increasing [MIDEA]. The decrease in D values with increasing [HNO3] is considered to be due to the effect of acid extraction with MIDEA. A plot of log D   values against log [MIDEA] was found to show the linear relationship with slope of ca. 1.1. This result suggests that one MIDEA molecule contributes to the extraction of ReO4−, i.e., 1:1 complex. This is supported by the fact that the ReO4− species extracted from HNO3 solution to CH2Cl2 phase containing MIDEA is assigned as [C13H28O2N3+][ReO4−] by the single crystal x-ray analysis.

► Extraction behavior of ReO4− from HNO3 solution to CH2Cl2 containing 2,2′-(methylimino)bis(N,N’-diethylacetamide) (MIDEA). ► Distribution ratios decrease with increasing [HNO3] and increase with increasing [MIDEA]. ► One MIDEA molecule contributes to the extraction of ReO4−. ► The extracted species is assigned as [C13H28O2N3+][ReO4−] by single crystal x-ray analysis.