New Synthetic Routes with Low Environmental Impact towards Mild Surfactants Starting from Renewable Starting Materials

Amino acid-based surfactants are mild surfactants that are mainly used as additives in personal care products such as shampoos, shower gels, hand soaps, etc. Due to their excellent cleaning properties, their demand has increased significantly over the past twenty years. An example of such surfactants are N-acyl amino acids, the molecular structure of which consists of an acyl group of fatty acids and an amino acid part. Schotten-Baumann acylation of amino acids is an industrial method of the N-acyl amino acids synthesis; acyl chlorides are used as the initial reactant. The reaction is carried out in water at a low temperature with excellent product yield. The most significant drawback of this process is the non-ecological route of acyl chlorides synthesis. Toxic reagents are used for their formation in stoichiometric quantities. Therefore, the aim of this work was to find a more environmentally friendly method for synthesizing N-acyl amino acids, allowing acyl chlorides to be replaced with other commercially available sources of fatty acids. Among the various approaches explored, we investigated both enzymatic synthesis, employing biodegradable and non-toxic biocatalysts, and thermal catalytic synthesis, typically conducted at elevated temperatures. Both these methods allowed us to perform the reactions, the efficiency of which exceeds current industrial method. Although not directly connected to the central aim of the PhD thesis, the final part of this work was conducted within the BOG research group at the University of Genova and focused on the conversion of levoglucosenone, a compound derived from cellulose-containing biomass, into high-value molecules.