Ultrasound-Assisted Syntheses of Chalcones: Experimental Design and Optimization

Abstract

Chalcones are a group of compounds that belong to the flavonoid family and have a wide variety of uses, including a high therapeutic potential for multiple diseases, such as, anticancer, antifungal or antibacterial agents. As is well known, chalcones are commonly synthesized by Claisen-Schmidt condensation, aldol condensation involving the appropriate aldehydes and ketones, in presence of acid or base as catalyst followed by dehydration reactions. However, under conventional conditions it is carried out with prolonged reaction times and requires expensive catalysts. For this reason, alternative source of energy, microwave or ultrasound, are employed. On the other hand, in all chemical processes a considerable amount of variables (instrumental parameters, reagents, temperatures, times, etc.) take part so a large number of experiments must be carried out in order to define the optimal conditions. In addition, the experimental design technique -important tool- allows the optimization of conditions leading to better yields in shorter times. Here and in line with previous research, we explore the synthesis, assisted by ultrasound, of (E)-1,3-diphenyl-2-propen-1-one like a model reaction. Taguchi Design was the mathematical method employed to determine the best working condition. In conclusion, the desired product is obtained quantitatively, without undesired by-products, and in short reaction times. Additionally, the reaction was used, as an alternative method, to monitor the ultrasound equipment using the control chart methodology (Shewhart chart), which allowed us to study how a process changes over time.