Research has been published using glycerol as a component in deep
eutectic solvents (DESs) [24]. DES are generally preparedbwith two classes
of compounds: hydrogen bond donors (HBDs) and hydrogen bond
acceptors (HBAs). HBDs are generally neutral, small, covalently bonded
molecules which are capable of hydrogen bonding, such as sugars,
polyols, and carboxylic acids. The HBAs are generally ionic compounds;
those studied most commonly thus far have been quaternary ammonium
salts [25]. DES solvent systems are similar to ionic liquids (ILs) in
many ways, possessing unusually low volatility, interesting chemical
and physical properties, reusability, etc. [26]. DESs offer several advantages
over ionic liquids, including lower cost, biodegradability, and simple
preparation from readily available and inexpensive precursors [25].