[LUM#8] Towards a greener chemistry

By revisiting the ancestral technique of mortar and pestle, researchers at theMax Moussseron Biomolecules Institute have developed mechanochemical processes that enable the production of new molecules without the use of toxic solvents. A further step towards greener chemistry.

Emmanuel Perrin/CNRS Photothèque

What do a jar of moisturizer, a migraine medication and a plastic bottle have in common? They are all products of organic chemistry. " Through its synthesis activities, this chemistry, which focuses on compounds containing carbon atoms, contributes to the preparation of a large number of everyday products," explains Frédéric Lamaty, a chemist at the Institut des biomolécules Max Moussseron (IBMM).

A kitchen that relies on a key ingredient: the solvent. " It's used to facilitate contact between the different products involved in the reaction, and to create new molecules ", explains the chemist. Problem: these organic solvents are far from neutral. " They are highly polluting for the environment, and are sometimes accidentally spilled into the environment, with serious consequences such as pollution of rivers, seas and water tables ", warns the researcher. Solvents are also toxic for those who handle them, and doubly hazardous to health, as these volatile, explosive and flammable products must be handled with extreme care.

How can this use be reconciled with the need to develop greener, more environmentally-friendly chemistry? To limit the damage, solvents can be recovered and recycled. " But there is a totally different, promising and innovative approach: the development of completely new processes that do away with the use of solvents by resorting to grinding," explains Frédéric Lamaty(A mechanochemical approach to access the proline-proline diketopiperazine structure, 2017, in Bildstein Journal of organoc chemistry).

An ancestral technique

New processes inspired by ancestral know-how. "It's nothing less than the mortar and pestle technique," explains the researcher. The idea is simple: by mechanically "mixing" different solid products, new molecules can be synthesized in the same way as solvents. Why has this technique, known as mechanochemistry, been neglected by organic chemistry for so long? " The idea that there could be no synthesis without a solvent was established among scientists as far back as antiquity, when mistranslations from Greek to Latin led to the extrapolation of a sentence by Aristotle postulating that liquids mixed better than solids ", explains Frédéric Lamaty.

This blunder has long hampered the development of solvent-free organic chemistry. " However, isolated works using tools as basic as mortar and pestle already demonstrated the possibility of carrying out organic chemical reactions using mechanochemistry. Although there are still very few researchers working on mechanochemistry, the technique could well develop to meet the challenges of greener chemistry. " To 'mix' solids even better, to use Aristotle's expression, chemists have recently turned to ball mill-type equipment capable of generating greater grinding efficiency with less effort on the part of the manipulator and larger quantities of product ", enthuses the chemist from IBMM, a pioneering laboratory in mechanochemistry with a team dedicated to this research for over 15 years.

Manufacturing medicines

Thanks to mechanochemistry, researchers are able to synthesize new molecules that are attracting enormous interest, particularly from the pharmaceutical industry. " For example, our team at IBMM has succeeded in producing a peptide, a bioactive molecule which is a very good candidate for the manufacture of a new drug ", explains the chemist. More comprehensive studies are now enabling us to envisage the production of peptide drugs prepared mechanochemically without solvents. " We are also working on the synthesis of new molecules that could be of major interest to the electronics industry", adds the researcher.

With cleaner molecules for greener chemistry, mechanochemistry has a bright future ahead of it. The need to adopt a sustainable development approach has led to the emergence of a breakthrough technology with original scientific spin-offs," notes Frédéric Lamaty. All that remains now is to convince a greater number of organic chemists of the scientific, technical, economic and ecological benefits of the method, especially as a promising new mechanochemical approach, this time using the reactive extrusion technique, is currently being developed."

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