Solventfree

Solventfree, also written as solvent-free or solventless, refers to chemical processes and formulations conducted without the use of added liquid solvents or with negligible solvent content. In practice, solvent-free methods aim to reduce or eliminate residual solvents in products and to minimize waste and environmental impact. The term is used across organic synthesis, polymer chemistry, pharmaceuticals, and materials science.

Common solvent-free approaches include mechanochemical techniques such as ball milling and grinding, melt processing and direct melt polycondensation, extrusion-based processing, and solid-state reactions. These strategies rely on physical forces, heat, or catalysts to promote transformations without solvent medium. In some cases, tiny amounts of solvent may be used as a liquid-assisted grinding (LAG) additive, but the goal remains minimal or zero solvent.

Applications include solvent-free synthesis of small molecules and APIs, melt or dry granulation in pharmaceutical formulation, polymerization and curing of coatings, and the preparation of inorganic and organic materials. Benefits include reduced environmental and safety risks, lower solvent purchase and disposal costs, simpler purification, and improved compliance with green chemistry principles. Limitations include slower reaction rates for some processes, difficulties in heat management and mixing at scale, moisture sensitivity, and restricted choice of chemistries and catalysts.

Solvent-free chemistry is part of the broader green chemistry movement and continues to evolve with innovations in mechanochemistry, reactive extrusion, and solventless catalysis, aiming to expand the range of reactions that can be performed without solvents and to enable scalable, sustainable manufacturing.