, Volume 24, Issue 2, pp 507-515
Date: 31 Jul 2012

Theoretical study on interactions between thiophene/dibenzothiophene/cyclohexane/toluene and 1-methyl-3-octylimidazolium tetrafluoroborate

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Abstract

It is critically important to understand the interactions between thiophene/dibenzothiophene/cyclohexane/toluene and 1-methyl-3-octylimidazolium tetrafluoroborate ([C8MIM]+[BF4]) due to desulfurization by ionic liquids. In this work, the structures of thiophene, dibenzothiophene, cyclohexane, toluene, [C8MIM]+[BF4], [C8MIM]+[BF4]-thiophene, [C8MIM]+[BF4]-dibenzothiophene, [C8MIM]+[BF4]-cyclohexane, and [C8MIM]+[BF4]-toluene were optimized systematically at the GGA/PW91/DNP level, and the most stable geometries were performed by NBO and AIM analyses. It was found that [BF4] anion tends to locate near C2–H2 and four hydrogen bonds between [C8MIM]+ and [BF4] form in [C8MIM]+[BF4]. There exist hydrogen bonds and C–H···π interactions between [C8MIM]+[BF4] and thiophene/cyclohexane/toluene, while the hydrogen bonding interactions, π···π and C–H···π interactions occur between [C8MIM]+[BF4] and dibenzothiophene confirmed by NBO and AIM analyses. The interaction energies between [C8MIM]+[BF4] and thiophene, dibenzothiophene, cyclohexane, toluene are 18.83, 20.93, 6.83, 12.99 kcal/mol, showing the preferential adsorption of dibenzothiophene and thiophene by ionic liquid, in agreement with the experimental results of dibenzothiophene and thiophene extraction by [C8MIM]+[BF4].