Hydrophobic natural alcohols based deep eutectic solvents: Effective solvents for the extraction of quinine

This work synthesized a series of hydrophobic natural alcohols based deep eutectic solvents (NADESs). These NADESs exhibited high extraction ability for quinine. The NADESs with lower viscosity and stronger hydrogen bond accepting ability (β) had stronger extraction ability. Quinine acted as hydrogen bond acceptor (HBA) for the hydrogen bonding between quinine and NADESs. The extraction efficiency of NADESs for quinine was higher than ionic liquid (IL), trichloromethane and ethyl acetate. After extraction, the NADES phase could be reused and quinine could be recovered from NADES phase via back extraction with 1.0% acetic acid aqueous solution as extraction solvent. The NADESs have the advantages of ease of preparation and high atom-economy and may be promising solvents for the extraction of bioactive compounds from natural sources compared with ionic liquids and conventional organic solvents.