Enthalpies of solution and enthalpies of solvation of chloro- and nitro-substituted benzenes in 1-butyl-3-methyl imidazolium based ionic liquids at 298.15 K: Additivity of group contributions

Abstract

In this work thermochemistry of solution and solvation of mono- and di-substituted chloro- and nitro-benzenes in 1-butyl-3-methylimidazolium tetrafluoroborate ([BMIM][BF4]), 1-butyl-3-methylimidazolium trifluoromethanesulfonate ([BMIM][TfO]) and 1-butyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide ([BMIM][NTf2]) ionic liquids was studied. Enthalpies of solution at infinite dilution of benzene, chlorobenzene, nitrobenzene, 1,2-, 1,3-, 1,4-dichlorobenzenes, 1,2-, 1,3-, 1,4-dinitrobenzenes, 1-chloro-2-nitrobenzene, 1-chloro-3-nitrobenzene, and 1-chloro-4-nitrobenzene in three ionic liquids were measured at 298.15K. On the basis of experimental data enthalpies of solvation of substituted benzenes in ionic solvents were calculated. Values of Cl and NO2 group contributions to the enthalpies of solvation were derived and compared with molecular solvents. Enthalpies of solvation of each series of dichlorobenzenes, chloronitrobenzenes and dinitrobenzenes in studied ionic liquids are equal and do not depend on the mutual position of substituents. This fact shows that dipole moment does not affect the enthalpy of solvation of organic solutes in ionic liquids. Enthalpies of solvation of disubstituted benzenes in ionic liquids calculated through group contribution approach were in good agreement with experimental data.