Polyamides exist in several different products, like parachutes of nylon, ropes for mountaineering, and materials for 3D printing. For these polyamides, dicarboxylic acids are utilized as chemical building blocks.
Professor Dr. Siegfried Waldvogel. Image Credit: Eric Lichtenscheidt
Nevertheless, their production has been difficult until now as the existing approaches of generating dicarboxylic acids from unsaturated or saturated hydrocarbons often involve many steps and the employment of strong acids and heavy metals. At the same time, the costs and related energy consumption are extensive.
In addition, the process frequently leads to the release of nitrogen oxides (NOx), which are among the most problematic greenhouse gases considering their impact on the climate. Scientists at Johannes Gutenberg University Mainz (JGU) and Evonik have recently developed an eco-friendly path to generate (di)carboxylic acids. The findings are published in Nature Communications.
Electrochemistry Provides New Opportunities
Our technique is the first-ever process to make the building blocks for polyamides from petrochemical compounds and even unsaturated fatty acids using a fairly sparing approach.
Professor Siegfried Waldvogel, Speaker, Mainz University
Professor Siegfried Waldvogel is the speaker of SusInnoScience – Sustainable Chemistry as the Key to Innovation in Resource-efficient Science in the Anthropocene.
The new approach includes an electrochemical method in which hydrocarbons with triple or double bonds are transported to an electrolysis cell filled with a solvent. Then, oxygen is added, where the higher the oxygen concentration, the higher the success of the process.
What is really fascinating about our process is that the electrochemical intervention is needed at both the anode and the cathode.
Professor Siegfried Waldvogel, Speaker, Mainz University
The oxygen at the opposite electrode is minimized to superoxide anions, where oxidative radicals are formed at the anode. The superoxide anions and radicals join in the solution and respond to generate carboxylic acid, the desired product. The scientists have efficiently repeated the process in flow and standard electrolytic cells.
Process Requires Only Oxygen, Electricity, and Hydrocarbon Compounds
This novel approach has several benefits: Strong acids and heavy metals are no longer necessary, and no nitrogen oxides are produced. The only starting materials required are electricity, oxygen, and hydrocarbons with double bonds. The process is very cost-effective as no byproducts are produced and the solvent can be recycled and recovered.
This is an innovative and less detrimental process for producing carboxylic acids, thus providing a valuable contribution to those manufacturers who wish to replace the climate-damaging processes with a green approach.
Professor Siegfried Waldvogel, Speaker, Mainz University
Currently, the research team is studying the scale-up of the lab process to make it functional for commercial use.
Journal Reference:
J. Nikl et al., Electrochemical oxo-functionalization of cyclic alkanes and alkenes using nitrate and oxygen, Nature Communications, doi.org/10.1038/s41467-023-40259-0.