Chemistry without solvents

The aim of green chemistry is to design chemical products and processes that reduce or eliminate the use and synthesis of hazardous and toxic substances. Chemistry "thought differently", accompanying changes in concepts and practices, will contribute to economically efficient and sustainable development. Consequently, new synthesis processes must include an ecological component. Part of chemistry's contribution to sustainable development is to reduce the quantity of by-products of chemical reactions and toxic waste. Reaction solvents, which are generally used in large quantities, fall into this category.

Many organic solvents are harmful from an ecological and public health point of view, and dangerous because they are often volatile and flammable. Alternative solvents have been proposed, such as water, ionic liquids or supercritical CO ₂ . However, the best solvent from an ecological point of view remains the absence of solvent, especially as once the usual dogma ("no reaction without solvent") has been overcome, it has been observed that the absence of solvent can be beneficial for the progress of a reaction. What's more, in some cases, one of the reagents, which is liquid, can act as a solvent for the reaction.

In a process, solvents are used at various stages: synthesis, purification and cleaning of equipment (such as reactors, for example). In this article, we focus on methods for eliminating solvents from chemical synthesis processes.