Sustainable menthol from a by-product of the paper industry
Potential to replace petroleum-based synthesis
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During paper production, considerable quantities of turpentine oil are produced, which were previously mainly burned to generate energy. A research project at Cologne University of Applied Sciences has now developed a new synthesis method that can be used to produce menthol for the pharmaceutical, food and cosmetics industries. In the long term, this could replace the synthetic petroleum-based menthol used to date.
"Turpentine oil is produced during paper production when wood fibers are overcooked. At the headquarters of our partner UPM Kymmene alone, this amounts to several 10,000 tons per year, which are then thermally recycled or converted into biodiesel. When considering alternative uses, we focused on the chemical compound 3-carene, which makes up around 30 percent of the oil and from which menthol can be produced. A major challenge here is separating the oil into its components," explains project leader Prof. Dr. Matthias Eisenacher from the Faculty of Applied Natural Sciences at TH Köln.
Separation column and nanofiltration
In order to extract the 3-carene from the turpentine oil, the project partners set up an approximately eight meter high separation column on a pilot plant scale at the Deutz campus. All components were custom-made in the workshop at TH Köln. "In our plant, so-called rectification takes place; a thermal separation process that separates the components of the liquid according to their boiling points. This is particularly difficult with turpentine oil because the boiling points of the individual substances are close together," explains research assistant Katharina Göbel from the Institute of Plant and Process Engineering at TH Köln.
The institute also investigated whether the oil can also be broken down into its components using organic nanofiltration and tested various commercial plastic membranes for this purpose. "This process has been little researched for organic solutions and is characterized by a relatively complex interaction between the starting substance, the valuable material and the membrane. We were able to achieve good results and prove that this process is a useful addition to rectification in order to obtain other substances in addition to the 3-carene," says Göbel. For example, alpha and beta-pinene were dissolved from the turpentine oil - organic hydrocarbon compounds that are used in medical applications, for example.
Synthesis in just a few steps
The chemical synthesis of 3-carene into menthol was developed in parallel. "It was particularly important to us that our process could also be realistically implemented in industry. We therefore wanted to get by with as few synthesis steps as possible and only use commercially available methods and plant components," says Eisenacher. Ultimately, the researchers need four steps, i.e. individual chemical transformations, to produce menthol. The first three steps are already practicable with a yield of 90 percent and more. "Despite all the optimization, the last step only achieves a yield of 65 percent. Further research is needed here, for example on the use of enzymes," says Eisenacher.
The project "Waste2Menthol - Synthesis of menthol from paper industry waste" was funded by the Federal Ministry of Education and Research via the FHprofUnt program with around 660,000 euros. The partners were Symrise AG, a manufacturer of fragrances and flavorings, and the paper manufacturer UPM Kymmene.
Note: This article has been translated using a computer system without human intervention. LUMITOS offers these automatic translations to present a wider range of current news. Since this article has been translated with automatic translation, it is possible that it contains errors in vocabulary, syntax or grammar. The original article in German can be found here.
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Topic world Synthesis
Chemical synthesis is at the heart of modern chemistry and enables the targeted production of molecules with specific properties. By combining starting materials in defined reaction conditions, chemists can create a wide range of compounds, from simple molecules to complex active ingredients.
Topic world Synthesis
Chemical synthesis is at the heart of modern chemistry and enables the targeted production of molecules with specific properties. By combining starting materials in defined reaction conditions, chemists can create a wide range of compounds, from simple molecules to complex active ingredients.