Chalcone Synthesis by Green Claisen-Schmidt Reaction in Cationic and Nonionic Micellar Media.

Abstract

In this paper, micellar-mediated synthesis of chalcones was explored. After optimization of the reaction conditions, the cationic surfactant CTAB and the nonionic one, Tween 80, were taken into consideration. Both surfactants were used to study the scope of Claisen-Schmidt reactants, and a wide scope on both aromatic aldehydes and methyl ketones was explored, obtaining from good to very good yields in most cases and thus demonstrating that the chalcones can be proficiently synthesized in micellar solutions with a wide functional group tolerability. Often, when one surfactant did not perform well, the other surfactant performed better, demonstrating that the use of different surfactants can constitute a good alternative to overcome reactivity problems. Besides, Tween 80 can be proposed as a good and greener alternative to CTAB in most cases. Some reactions gave low yields, showing that some specific improvements would be needed to address the low reactivity. The micellar medium was studied by NMR to search for information about the association of the Claisen-Schmidt reactants with the micelles and their locations within them. Diffusion Ordered Spectroscopy (DOSY) was applied to assess the interaction and the percentage of incorporation of reactants into the micelles.