Electrophilic aromatic substitution in eutectic-type mixtures: from an old concept to new sustainable horizons

Abstract

The Friedel–Crafts reaction is present in many fields of chemistry, being especially relevant in industrial applications, where it is one of the key methodologies to transform raw materials into functionalized aromatic products. During the last few years, the industry has been compelled to modify the conditions applied in its processes owing to the demand for more environmentally conscious and safe production techniques. In this review, some alternatives to conventional solvents, such as the use of deep eutectic solvents (DESs) as new reaction media with compatible catalysts, commonly used in Friedel–Crafts reactions are reported. These new conditions represent a major step towards sustainability in comparison to traditional methods, which employ stoichiometric amounts of Lewis acids and organic volatile solvents as reaction media.