Green Chemistry at work in cosmetics: the example of Pro-Xylane
L'Oréal researchers chose to start with a natural sugar extracted from beech wood: xylose, a renewable raw material. It was ground, dissolved in water (a particularly harmless solvent), reacted in the presence of hydrogen and, after a few hours of agitation, heated slightly with a catalyst. Pro-Xylane was thus obtained. Its synthesis is composed of only two stages and makes it a very sustainable molecule.
This synthesis was inspired by a very innovative chemical reaction published in 2000 by Prof. André Lubineau, Paris-Sud University. Indeed, it makes it possible to reduce by four the number of chemical steps necessary to obtain C-glycosides, the chemical family to which Pro-Xylane belongs. In addition, this reaction also allows for the use of water as the sole reaction solvent in place of the usual organic solvents.
The industrialization processes for the synthesis of this molecule were also optimized to further respect the environment: we were particularly interested in the amount of waste generated during large-scale synthesis. The Environmental Factor (or E factor) translates the relationship between the tonnage of waste and the tonnage of the desired molecule: the lower this ratio, the less polluting the molecule. For Pro-Xylane in solution, the E factor was 13, which — on a scale from 5 to 50 — is a very good coefficient. It was then further improved.
Once the efficacy of the molecule was demonstrated, its impact on the environment was also verified through ecotoxicity tests, conducted both internally and externally. They consist in verifying whether a substance is likely to cause harmful effects on species and on ecosystems. In practice, these tests relate to three types of living microorganisms in the food chain.
Furthermore, Pro-Xylane is a molecule that is poorly soluble in fats: it is therefore not thought to bioaccumulate in food chains.
In addition to these tests, other studies verify that the molecule is not toxic to humans.
Once these verifications have been carried out, the molecule is synthesized, then formulated with other ingredients to give birth to a finished product. Here too, its sustainable substance qualities reveal precious advantages in the formulation. On the one hand, its storage over time is easy, because, once dissolved, it does not require preservatives. On the other hand, its association with other ingredients is facilitated by the fact that once in solution in water, it is easily incorporated at the end of the formulation without having to use energy.
Energy, material and time savings: an initiative for the future
At L'Oréal, several indicators of sustainable processes have been introduced into the work of laboratories to — beginning at the design stage —preferably select the processes that make it possible to limit the quantities of waste. Significant efforts have also been made to upcycle plant biomass and identify, in close collaboration with suppliers of raw materials, those based on environmentally friendly processes. In 2019, our portfolio includes 28% of raw materials faithful to the principles of Green Chemistry. Each year we include new ones.