Hansch’s analysis application to chalcone synthesis by Claisen–Schmidt reaction based in DFT methodology

Chalcones are bioactive compounds obtained from either natural sources or synthetic procedures and widely used due to their several biological properties. The most common experimental methodology in obtaining these compounds is Claisen–Schmidt reaction, which is a particular type of aldolic condensation. In this work, we have synthesized 23 chalcones and by density functional theory (DFT) calculation, we have studied the difference in reactivity of the several benzaldehydes and their effects on the yield of this reaction. From molecular orbital descriptors were obtained two quantitative structure–reactivity relationship (QSRR) models based on Hansch’s analysis. The results of this study showed that, for the most benzaldehydes (15 of 23 compounds), their reactivity was correlated with LUMO energy and global Electrophilicity Index (ω) values, which are determined in the first step of Claisen–Schmidt condensation mechanism (nucleophilic addition). Likewise, for the smallest group of benzaldehydes, their reactivity was related to their HOMO and ΔL − H (LUMO − HOMO) energies, which were determined in the second step of the mechanism (trans-elimination). This is the first report of a QSRR model analyzing the yield of chalcone synthesis based on DFT methodology.