Introducing Students to Mechanochemistry via Environmentally Friendly Organic Synthesis Using a Solvent-Free Mechanochemical Preparation of the Antidiabetic Drug Tolbutamide

The implementation of environmentally friendly, solvent-free mechanochemical synthesis in an undergraduate chemistry teaching laboratory is described. As a model reaction, the experiment addresses the catalytic mechanochemical synthesis of a small library of sulfonylureas, including a known active pharmaceutical ingredient, tolbutamide. The experiment introduces students to mechanochemistry, and the use of automated ball milling as a solvent-free synthetic methodology with a choice of two instruments: a mixer mill and a planetary ball mill. The isolation and purification of final products is achieved simply by washing with water and characterization is performed through powder X-ray diffraction. As milling reactions under wet and dry conditions lead to the formation of two diverse polymorphs of tolbutamide, this experiment also provides an opportunity to discuss topics relevant to solid-state pharmaceutical materials science, such as crystal packing of molecules and polymorphism, and it is an illustration of the emergent field of medicinal mechanochemistry in an undergraduate teaching laboratory.