[LUM#8] Towards greener chemistry
By revisiting the ancient 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. This is another step toward greener chemistry.
What do a jar of moisturizer, a migraine medication, and a plastic bottle have in common? All of these products are derived from organic chemistry. "Through its synthesis activities, this branch of 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 Max Moussseron Institute for Biomolecules (IBMM).
A kitchen that uses a key ingredient: solvent. "It is used to facilitate contact between the different products undergoing reaction and create new molecules," explains the chemist. The problem is that these organic solvents are far from neutral. "They are highly polluting for the environment and can sometimes be accidentally spilled into the natural environment, with serious consequences such as pollution of rivers, seas, and groundwater," warns the researcher. Solvents are also toxic to those who handle them and doubly dangerous to health, as these volatile, explosive, and flammable products must be handled with extreme caution.
How can this use be reconciled with the need to develop green chemistry that is more environmentally friendly? To limit the damage, solvents can be recovered and recycled. "But there is a completely different, promising and innovative approach: the development of entirely new processes that do away with the use of solvents by resorting to grinding," explains Frédéric Lamaty (A mechanochemical approach to accessing the proline-proline diketopiperazine structure, 2017, in Bildstein Journal of Organic Chemistry).
An ancient technique
New processes inspired by ancestral know-how. "It's nothing more 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 with solvents. Why has this technique, known as mechanochemistry, been neglected for so long by organic chemistry? "The idea that synthesis could not take place without solvents became established among scientists in ancient times, when translation errors from Greek to Latin led to the extrapolation of a sentence by Aristotle postulating that liquids mixed better than solids,"explains Frédéric Lamaty.
A blunder that long hindered any development in solvent-free organic chemistry. "However, isolated studies using tools as basic as mortars and pestles had already demonstrated the possibility of carrying out organic chemical reactions through 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, as Aristotle put it, chemists have recently turned to ball mill-type equipment capable of generating greater grinding efficiency with less effort on the part of the operator and larger quantities of product, "says the IBMM chemist, a pioneering laboratory in mechanochemistry with a team dedicated to this research for over 15 years.
Manufacturing drugs
Thanks to mechanochemistry, researchers are able to synthesize new molecules that are attracting enormous interest, particularly from the pharmaceutical industry. "Our team at the IBMM, for example, has succeeded in producing a peptide, a bioactive molecule that is a very good candidate for the manufacture of a new drug," explains the chemist. More comprehensive studies now make it possible to consider the production of peptide drugs prepared without solvents using mechanochemistry. "We are also working on the synthesis of new molecules that could be of major interest to the electronics industry,"says 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 disruptive technology with original scientific implications," notes Frédéric Lamaty. All that remains is to convince more organic chemists of the scientific, technical, economic, and ecological benefits of the method, especially since a promising new mechanochemistry approach, this time using reactive extrusion technology, is currently being developed."
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