Synthetic Procedure
Ricinoleate anion-based ionic liquids having four variable nitrogen containing cations were synthesized by a facile metathesis reaction as per the earlier reported procedure (Gusain et al., 2016). The reaction proceeds in a single step by stirring equimolar ratio of both bromide salt and sodium ricinoleate in water for 18 h. The reaction mixture was extracted by using dichloromethane (DCM) followed by washing with distilled water to remove excess sodium ricinoleate and sodium bromide. The solvent was removed under reduced pressure and the obtained ionic liquids were dried for 48 h at 80 °C. The synthesized four ionic liquids tetrabutylammonium (Z)-12-hydroxyoctadec-9-enoate (TBA-RA), tetrapropylammonium (Z)-12-hydroxyoctadec-9-enoate (TPA-RA), N,N,N-trimethylhexadecan-1-aminium (Z)-12-hydroxyoctadec-9-enoate (CTB-RA), 1-butyl-3-hexyl-1H-imidazol-3-ium (Z)-12-hydroxyoctadec-9-enoate (BHI-RA) were characterised by NMR and FT-IR.