Eco-friendly one pot synthesis of caffeic acid phenethyl ester (CAPE) via an in-situ formed deep eutectic solvent

• A new, green synthesis of caffeic acid phenethyl ester is carried out in a deep eutectic solvent.
• The novelty is that caffeic acid is both part of the solvent and one of the reactants. No solvent is required.
• The deep eutectic solvent contains choline chloride, an environmentally friendly salt that can be easily recovered.

In this paper, a new strategy towards the synthesis of caffeic acid phenethyl ester (CAPE) is introduced. The reaction is carried out in a deep eutectic solvent made of caffeic acid and choline chloride. Caffeic acid is used as part of the solvent and as reactant. Phenethyl alcohol is soluble in this mixture in every molar ratio, and as a consequence no additional solvent is necessary. Reaction conditions were optimised with respect to the molar ratio of phenethyl alcohol and caffeic acid, and by varying the amount and nature of the acid catalyst as well as the reaction time. The obtained CAPE ester could easily be separated from the reaction mixture by simply adding water to destroy the deep eutectic by solubilisation of choline chloride in the aqueous phase.

A simple method of a transient in-situ creation of a solvent allows an environmentally friendly synthesis of a pharmacologically relevant molecule.Figure optionsDownload as PowerPoint slide