Grignard reagent and Green Chemistry : Mechanistic studies to understand the molecular origins of selectivity in the formation of RMgX

Controlling selectivity is one of the important keywords in the development of Green Chemistry. The mechanistic study of the formation of RMgX with the aim of understanding at which step(s) the selectivity is settled shows that there is room for basic research in a field too often considered as the simple development of new recipes. One of the most widely used reactions in synthetic studies still offers fascinating conundrums when one tries to answer the apparently simple question: at which step(s) does the formation of by-products coexisting with RMgX occur? Here the illustration of this statement is given by studying the patterns of reactivity of aliphatic and aromatic radical clock halides toward magnesium or potassium. The importance of using the concepts developed by electrochemists to rationalize the selectivity observed at cathodes or anodes for understanding selectivity observed in the reactive dissolution of metals is stressed.