LAUSR

A two-step strategy was attempted to develop the best amino acid-based basic ionic liquids for catalytic production of biodiesel via transesterification. Cholinium with various amino acids as paired anions were first synthesized to screen anionic moiety. Arginine and histidine were selected for further structural evolution by varying the substituents of tetraammonium cation. Tetrabutylammonium arginine ([TBA][Arg]) was found to be the most effective catalyst to obtain 98.0%–99.8% yield of biodiesel at 80 °C within 15 min with catalyst loading of 28.84 mmol/100 g high oleic sunflower oil. 13C NMR spectra of reactants and products certified the progress of transesterification structurally. Biodiesel yield of 98.80% was obtained under the optimal conditions: catalyst loading 6% (oil basis, w/w), temperature 90 °C, methanol to oil mole ratio 9:1, and 15 min reaction. The catalytic transesterification by [TBA][Arg] was applicable for different alkyl alcohols, but the activity decreased with increasing alkyl ch...