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.