Hydrogen bond induced acidic liquids for efficient biodiesel production

Abstract In chemical engineering, the Fischer–Speier esterification shows incredible value for biofuel production. However, the transformation suffers from challenges including necessary catalysts that cause corrosion issues in addition to a complex synthesis. Herein, we report a green acidic liquid, [N,N,N‐tris(propanesulfonic)aniline][ethanol] 3 , which is induced by hydrogen bonding interactions between a hydrogen bond acceptor (HBA) of [N,N,N‐tris(propanesulfonic)aniline] and three hydrogen bond donators (HBD) of ethanol, through a one‐step reaction. This liquid demonstrates strong Bronsted acidity and hydrogen bond networking to mimic ionic liquids (ILs) or deep‐eutectic solvents (DESs). Even under mild conditions, biodiesel was produced with 97.65% of esterification conversion. Exploiting distinguished molecular geometry with a singular methodology, made possible by contributions from HBD, allows for a further reaction of 1,3‐propanesulfonate with positively charged amines. This discovery is feasible with a wide range of HBDs as a solvent resulting more commercially accessible products owing to a much greener synthesis when compared with ILs and DESs.