The Extraction of Several Anions by Methyltrioctylammonium into Various Solvents

TLDR: In this article, the back extraction of methyltrioctylammonium chloride (MTOACl) from ten kinds of organic solvents was investigated as a function of the ammonium concentration, and the selectivity coefficients (KX/Cl) of MTOA for the exchange of Br−, I−, ClO4−, vs.

Abstract: The back extraction of methyltrioctylammonium chloride (MTOACl) from ten kinds of organic solvents was investigated as a function of the MTOACl concentration. The chemical species of the ammonium salt in the organic phase were found to be in the form of dissociated ions, of ion pairs, or of dimeric ion pairs, according to the dielectric constant of the solvent. MTOACl was better extracted into more polar and acidic solvents, such as nitrobenzene, 3-methyl-1-butanol, and chloroform. The selectivity coefficients (KX/Cl) of MTOA for the exchange of Br−, I−, ClO4−, vs. Cl− were obtained from the study of the distribution of several organic color reagents; they were found to increase with the anion size, irrespective of the organic solvent used. For all but acidic solvents, the values of KX/Cl were similar to each other. Such acidic solvents as 3-methyl-1-butanol and chloroform, however, reduced the selectivity of the extraction for anions.