Mi. Zaretskii et al., SELECTION OF EFFECTIVE SOLVENTS FOR THE SEPARATION OF FLUOROAROMATIC COMPOUNDS BY EXTRACTION RECTIFICATION, Journal of applied chemistry of the USSR, 65(10), 1992, pp. 1854-1857
It has been established, from a study of complex formation in solution
using F-19 NMR spectroscopy, that this method can be successfully use
d in the search for and selection of extractants for separating aromat
ic compounds with similar boiling points by extraction rectification.
Effective extractants (at 60-degrees-C) have been identified as gamma-
butyrolactone (for separating the meta and para isomers of difluoroben
zene) and 2-pyrrolidone (for separating metadifluorobenzene and fluoro
benzene).