Reactions of organic synthesis in ionic liquids

Today, one of the major objectives of synthetic organic chemistry is to research, discover and exploit environmentally-friendly methods. Indeed, sustainable development is a crucial issue, the importance of which was recently symbolized by the award of the Nobel Peace Prize in 2007. Gigantic challenges are met by multiple approaches. The aim is to achieve development that is socially equitable, ecologically sustainable and economically viable, in accordance with the 3 "E's" (equity, environment, economy, French interpretation of the 3 "P's": people, planet, profit). Contributing to this approach is becoming essential, particularly in the chemicals sector. Expectations are pressing from the general public, regulatory bodies and all industrial sectors where chemistry has applications. Chemistry also has a role to play in environmental issues such as global warming associated with greenhouse gas emissions. This new chemistry must focus on prevention. It must design and implement clean, safe processes that are less costly in terms of raw materials and energy, and that limit the production of waste and effluents. The treatment and elimination of effluents must therefore be taken into account from the earliest stages of research into new processes. The aim of developing "green" chemistry is not to eliminate waste, but rather to avoid producing it! This trend is already underway: more efficient synthesis methods, activation, catalysis, process optimization and intensification, high-performance treatment techniques - these are just some of the avenues currently being explored by chemists.

The vast majority of synthesis reactions in fine chemistry are carried out in organic solvents. However, as mentioned above, environmental concerns are a major preoccupation in the world of industrial and academic research. One of the priorities on which a number of approaches are converging is to replace or even eliminate organic solvents, members of the VOC (Volatile Organic Compounds) family responsible for damaging the ozone layer, and thus contributing to global warming. In the field of synthesis, organic solvents are very often indispensable for carrying out reactions, enabling reactive molecules to come into effective contact, adjusting the viscosity of the reaction system, or acting as a "thermal buffer", indispensable in the case of exothermic reactions. On the other hand, this convenience brings with it disadvantages that are no longer acceptable in today's society: toxicity, often flammability, VOC emissions and so on. While these solvents will not disappear completely, it is true that green chemistry concepts are leading us to systematically rethink their use. Some have proposed developing solvent-free reactions. Others have envisaged the use of new media such as microemulsions, supercritical fluids,...