The Syensqo company, comprising the solutions, activities and markets represented in the article below, was spun off from Solvay group in December 2023.
Synthesizing eugenol at Solvay
Traditionally extracted from clove oil, eugenol is used in flavor and fragrance (F&F) and also for dental care applications, thanks to its strong analgesic and antiseptic properties. Eugenol is also used as an intermediate to produce specialty polymers. Like with vanillin, it’s possible to artificially create a perfect replica of the natural molecule. At least, that was the theory...
Several attempts to produce synthetic eugenol have been made over the past decades, but the first company to successfully achieve this tricky feat at large industrial scale was Solvay, thanks to the work of its Aroma Performance team at Saint Fons Spécialités, near Lyon, France.
Overcoming every hurdle
Eugenol production is concentrated in Madagascar and Indonesia, but growing cloves requires optimal climatic conditions, and variations in production yields tend to create price variations. Coupled with a sharp increase in demand for eugenol in recent years, price fluctuations have been an increasing problem for the Flavors & Fragrance industry.
Always keeping an eye on trends in customer demand, the Aroma Performance team, which had already successfully developed Rhovanil® Natural, decided to tackle the challenge of producing synthetic eugenol. In only two years, between 2019 and early 2021, they managed to overcome every hurdle and go from studying project feasibility to producing the first 40 tons of a brand-new product: Eugenol Synth.
“Solvay’s customers are interested in a synthetic alternative in order to ensure stable pricing as well as dependable quality and supply,” explains Corinne Duffy, Technical Marketing Manager and Eugenol Synth project leader. “Our value proposition is to guarantee that, close to our customers in Europe. Production of Eugenol Synth started in November 2020: it was challenging in the current circumstances, but the new product is now ready and sales have begun.”
The challenge of molecular selectivity
The reason why there were no significant volumes of synthetic eugenol on the market so far “is because nature is very selective,” explains Laurent Garel, R&I Lab Manager at Aroma Performance in St Fons. “There actually exist two similar molecules: para-eugenol and ortho-eugenol. Nature only produces para-eugenol, the one responsible for the typical clove fragrance, but past attempts to produce it yielded high proportions of ortho-eugenol in the process.” As it happens, the two molecules are extremely difficult to separate, so none of those attempts were economically viable, not to mention they were environmentally unsound because of the high quantities of by-product to dispose of.
Our innovation process isn’t just about chemistry. We define specifications according to market need, look at the existing literature and patents, come up with ideas for reactions, and then it’s all about trial and error.
The success with Eugenol Synth lies in the fact that Laurent’s team found a way to produce 98% pure para-eugenol. “This is both a chemical and environmental feat: high selectiveness means less waste,” he says. But how did they succeed where others had failed? “Our innovation process isn’t just about chemistry. First, we defined the specifications with our marketing and sales teams according to market need; in this case, purity was the priority, along with olfactive properties and reaction yield. From there, we looked at the existing literature and patents, similar reactions we can get inspiration from, our chemists came up with ideas, and then it’s all about trial and error. Separation processes are also key.”
Moreover, it must be said that the success of this project is also due to the good interactions between the R&I and industrial teams. The latter played a key role in the setup of the manufacturing process in the production plant.
A key ingredient and a promising by-product
Ultimately, once integrated into the formulations of F&F manufacturers, which are in turn skillfully combined by perfumers, the clove fragrance of eugenol is rarely recognizable when you open a bottle of perfume or cosmetics. But it’s a key ingredient nevertheless, and one of the world’s leading players in the industry is the very first customer for Eugenol Synth – in fact, the Swiss multinational collaborated with Solvay to obtain the perfect product. “It was a typical case of co-construction,” adds Laurent. “We knew what they wanted and sent them samples for feedback as we were developing the product; there were multiple interactions throughout the process.”
But what about the ortho-eugenol and other by-products that can’t help but be produced? A solution might have already been found for it... in materials! “This molecule has the property of reacting with certain functions in polymers,” explains Laurent. “You could, for example, add eugenol as an anchoring base for other molecules, providing additional properties and functionalities. We will undoubtedly find an application for ortho-eugenol in materials.” But sadly, they won’t smell like cloves…
