Title : Mechanochemical synthesis of thioureas and guanidines
Abstract:
Guanidines are interesting molecules containing carbon surrounded by three nitrogen atoms, with unique structural characteristics that contribute to their remarkable physico-chemical properties. In particular, their high basicity (superbasicity) and ability to form hydrogen bonds set them apart from other organic compounds. Their physico-chemical properties make guanidines valuable functionality in various applications, including their use as neutral, organic catalysts or components of receptor functionalities in anionic sensors. Various guanidine derivatives are widely distributed in nature, and they have also been explored synthetically. Numerous synthetic routes and reagents have been employed for guanidine synthesis. Recently, mechanochemistry has been recognized as a sustainable, solvent-free alternative to conventional organic solution-based synthesis. This solid-state approach offers several benefits, such as eliminating solvents, reducing chemical usage, simplifying the experimental procedures, and shortening reaction times. Consequently, mechanochemical synthesis often provides higher reaction yields in more environmentally friendly conditions than solution synthesis. In this presentation, solution and mechanochemical methods for the synthesis of thioureas and guanidines will be presented and their efficiencies will be compared. Synthetic routes starting from aromatic amines, the preparation of isothiocyanates, followed by aromatic thioureas, and finally substituted guanidines will be discussed.
