Altering Product Selectivity by Mechanochemistry

TLDR

Mechanochemistry, achieved by grinding, shearing, pulling, or milling, enables solvent‑free, high‑yield reactions with insoluble reactants, shortens reaction times, and can alter reactivity and selectivity compared to solution processes, sometimes yielding different product mixtures or trapping elusive intermediates. This Perspective highlights selected examples demonstrating how mechanochemistry can uncover reactivity that is masked in typical liquid‑phase synthesis.

Abstract

Mechanochemical activation achieved by grinding, shearing, pulling, or milling opens unique opportunities in synthetic organic chemistry. Common features are that mechanochemistry facilitates reactions with insoluble reactants, enables high-yielding solvent-free synthetic procedures, and shortens reaction times, among others. However, mechanochemical techniques can also alter chemical reactivity and selectivity compared to the analogous solution-based protocols. As a consequence, solvent-free milling can lead to different product compositions or equilibration mixtures than in solution. Reactions by milling have also allowed the trapping and characterization of elusive intermediates and materials. In this Perspective we highlight a few selected examples that illustrate the value of mechanochemistry in uncovering interesting chemical reactivity, which is often masked in typical liquid-phase synthesis.