mechanochemistry

Mechanochemistry refers to chemical transformations that are driven by mechanical force, such as grinding, milling, or shearing. It often proceeds under solvent-free or low-solvent conditions, using mechanical energy to initiate bond formation and disrupt solid-state structures.

The field includes ball milling, twin-screw extrusion, vibro-milling, and ultrasound-assisted mechanochemistry. Ball milling is widely used; extrusion enables scalable continuous processing; liquid-assisted grinding uses small amounts of solvent to improve reaction rates and selectivity (LAG). Mechanochemical methods have been used to synthesize organic bonds (C–C, C–N, C–O), inorganic materials, and polymers, enabling Kno-evenagel condensations, amidations, esterifications, and cross-couplings.

Mechanisms are complex and can involve generation of defects and vacancies, enhanced surface contact, localized heating, shock waves, and transient reactive species; catalysts and additives can steer selectivity. The efficiency depends on parameters like milling speed, ball size, material, atmosphere, and presence of liquid additives.

Advantages include reduced or eliminated solvent use, often shorter reaction times, simpler purification, and potential energy savings; challenges include energy requirements, material wear, heat management, and reproducibility; scaling up to industrial scales is advancing through extrusion and continuous-flow mechanochemistry.

Mechanochemistry links to green chemistry and materials science, with applications from synthesis of pharmaceuticals to battery materials and catalysts. It remains interdisciplinary, spanning synthetic chemistry, physics, materials science, and chemical engineering.