“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 made accustomed to seeking solutions that are
not only efficient and cost-effective but also safe and environmentally
friendly. However, it is still a great challenge to select appropriate
material for a lecture that, in addition to providing educational
aspects, will simultaneously attract students’ attention. Therefore,
to make learning more accessible and inspiring, it is worth using
known molecules with interesting properties, such as denatonium salts,
as the main product of the developed sustainable process. In this
particular project, lidocaine was alkylated with benzyl chloride in
the presence of a catalyst and subsequently subjected to an ion exchange
reaction. This path resulted in the 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 to green chemistry principles, 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.