title: Role of alkyl group in the aromatic extraction using pyridinium-based ionic liquids.
abstract: The performance of N-alkylpyridinium-based ionic liquids with a SCN anion (PyILs) was evaluated for the selective extraction of aromatics from aliphatic hydrocarbons. The aromatic extraction ability of PyILs was greatly enhanced by the presence of a methyl group on the pyridinium ring at the 3- or 4-position, whereas the solubility of the aromatics in the PyILs decreased with increasing the number of methyl groups on the benzene ring. The FT-IR studies revealed that the solubility of an aromatic compound in a PyIL is closely correlated with the degree of aromatic C-H bending frequency shift observed during the dissolution of the aromatic compound in the PyIL: the larger the shift, the higher the solubility. The computational calculations on the dispersion interactions between aromatics and PyILs demonstrated that the anion-aromatic interaction is much more important than the cation-aromatic interaction in determining the aromatic solubility in PyILs, and such anion-aromatic interaction can be enhanced by introducing a methyl group at the carbon atom of the pyridinium ring.
authors.affiliation: Department of Chemistry and Research Institute of Basic Sciences, Kyung Hee University , 1 Hoegi-dong, Dongdaemun-gu, Seoul 130-701, Republic of Korea.
authors.forename: Min Ji
authors.initials: MJ
authors.lastname: Kim
authors.forename: Seung Hoon
authors.initials: SH
authors.lastname: Shin
authors.forename: Young Jin
authors.initials: YJ
authors.lastname: Kim
authors.forename: Minserk
authors.initials: M
authors.lastname: Cheong
authors.forename: Je Seung
authors.initials: JS
authors.lastname: Lee
authors.forename: Hoon Sik
authors.initials: HS
authors.lastname: Kim