Eugenol :
A new route
Solvay has unveiled a synthetic route to eugenol . Technical market manager Corinne Duffy explains why
Natural eugenol is an aromatic
substance that is traditionally extracted from clove oil . This is obtained from dried flower buds of clove trees grown in Indonesia and Madagascar . Eugenol has a typical strong , spicy , clove odour . It is used in flavours and fragrances ( F & F ) and in dental care applications like toothpaste and mouthwash , thanks to its strong analgesic and antiseptic properties . It also finds uses as an intermediate in the production of speciality polymers . A synthetic route to eugenol was initially developed by scientists at Rhône-Poulenc , the predecessor of Rhodia , which in turn became part of Solvay , in the early 2000s . However , the process never progressed beyond the pilot stage . This was partly because of technical challenges in purifying the final product that rendered the process economically unattractive , but mostly because the market was not ready . Growing cloves requires optimal climatic conditions , while variations in yields tend to create tensions in the supply chain . In recent years , there has been a sharp increase in demand for eugenol and prices have fluctuated up and down . Indeed , price fluctuations for products of natural origin , notably in tropical regions , have been an increasing problem for the F & F industry in general . As with the flavour molecule vanillin , it is possible to artificially create a replica of the natural eugenol molecule . Solvay scientists therefore revisited the process , focusing on increasing yields and improving the separation stage . The first step was to define specifications , including olfactive properties , in collaboration with customers . The research and innovation ( R & I ) teams took their inspiration from looking at patents and literature , and also by brainstorming sessions with other Solvay teams . The chemists came up with ideas , which were tried at lab scale until the best route was found . An important aspect of the development process was to limit the amount of waste and find the safest process possible to be implemented at the plant in St Fons , France . The R & I teams worked on the reaction to improve the yields and conversion to the right product , while the process and industrial teams worked in real scale on the purification of the product . The resulting process begins with phenol , which is converted into catechol , and then into the intermediate guaiacol . This can be used in many other applications , including as an intermediate in the production of vanillin and the cough suppressant guaifenesin , as well as the main raw material for the production of eugenol . A specific distillation stage separates the desired end product , para-eugenol , from various co-products and by-products with similar boiling points . Solvay has patented the process and has used specific competencies to develop the process in particular olfactive evaluation , separation techniques and process safety . The company produced commercial-grade quality right from the start but is looking to further improve yields and also expand production . The synthesis route is potentially applicable to other fragrance materials . Synthetic eugenol is now available to the fragrance market , but in the near future , the product could be incorporated into dental care products , once Solvay secures the necessary certifications . Other markets where a natural origin is not required , such as polymer intermediates , also have potential . •
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Corinne Duffy
TECHNICAL MARKET MANAGER
SOLVAY corinne . duffy @ solvay . com www . solvay . com
44 SPECIALITY CHEMICALS MAGAZINE ESTABLISHED 1981