"Bitter" Results: Toward Sustainable Synthesis of the Most Bitter Substances, Denatonium Saccharinate and Denatonium Benzoate, Starting from a Popular Anesthetic, Lidocaine

One of the most important aspects associated with the modern production of chemicals is sustainability. To teach students and young scientists to design their research in the spirit of sustainable development, students should be madeaccustomed to seeking solutions that are not only efficient and cost-effective but alsos afe and environmentally friendly. However, it is still a great challenge to selectappropriate material for a lecture that, in addition to providing educational aspects, willsimultaneously attract students'attention. Therefore, to make learning more accessibleand inspiring, it is worth using known molecules with interesting properties, such asdenatonium salts, as the main product of the developed sustainable process. In thisparticular project, lidocaine was alkylated with benzyl chloride in the presence of acatalyst and subsequently subjected to an ion exchange reaction. This path resulted inthe formation of two organic salts, denatonium benzoate and denatonium saccharinate,which are considered the most bitter substances currently known to mankind. Additionally, their syntheses were optimized according togreen chemistryprinciples, and subsequently, the structures of the products were identified via spectroscopic methods (FTIR and NMR spectroscopies). Finally, determination of basic physicochemical parameters (solubility in water and octanol-water partition coefficient), according to OECD guidelines, enabled the assessment of the potential impact of these compounds on the natural environment