The solvent free synthesis of six chalcones was carried out by grinding the piperanal and the acetophenone (unsubstituted, 4-methyl, 4-methoxy, 4-bromo, 4-nitro, 3-chloro) in the presence of solid sodium hydroxide with a mortar and pestle. In general, the chalcones were obtained in high yield and high purity. Minor quantities of Ketol and Michael addition product were easily removed by recrystallization. The result indicates a correlation between the success of the solvent-free synthesis and melting point of the chalcone. Chalcone with relatively high melting points (higher than 80 ° C) were obtained in high yields. The two chalcones that could not be produced in good yields were having relatively low melting points. They have been screened for their antibacterial activity against Gram positive and Gram negative bacteria.
K. Saini, K. R., Choudhary, S. A., Joshi, Yogesh. C., & Joshi, P. (2012). Solvent Free Synthesis of Chalcones and their Antibacterial Activities. E-Journal of Chemistry, 2(4), 224–227. https://doi.org/10.1155/2005/294094