Scientists at Johannes Gutenberg University Mainz (JGU) and the ETH Zurich have developed a process with which so-called basic chemicals can be produced much more safely than before. Basic chemicals form the basis for many mass products in the chemical industry, such as plastics, dyes or fertilizers, and are usually produced using chlorine gas or bromine, both of which are very toxic and highly corrosive. As the researchers in the current issue of Sciencereport, they use electrolysis, i.e. the supply of electrical current, to obtain so-called dichlorides and dibromides and thus to produce basic chemicals. "Chlorine gas and bromine are difficult to handle, especially for small laboratories, due to the high safety requirements," says Prof. Dr. Siegfried Waldvogel, spokesman for the top research area SusInnoScience at JGU, who helped develop the new process. "Our method largely renders safety precautions superfluous because we do not use chlorine gas or bromine for this and the reaction for the synthesis of the basic chemicals can also be easily controlled via the supply of electrical current."
According to Waldvogel, electrolysis enables dichlorides and dibromides, among other things, to be obtained from solvents that are otherwise used to manufacture PVC. "It's much easier than making dichlorides and bromides from chlorine gas or bromine." The research team has proven that the new method works as desired with more than 60 reactions. "The process can be applied to molecules of different sizes and is therefore of general importance. It can also be easily scaled up, we have already been able to convert larger amounts of grams," says Waldvogel. He is particularly pleased with the discovery that with the help of electrolysis, the chlorine atoms can also be separated from the molecules of insect repellants, which are now banned, and dichlorides can thus be obtained. "Such insect repellants are practically not broken down naturally," says Waldvogel. "They therefore remain in the environment for an extremely long time and are now even found in the Arctic. We can now help with disposal and use the toxic substances to create value."
Dong X, Roeckl JL, Waldvogel SR, Morandi B. Merging shuttle reactions and paired electrolysis for reversible vicinal dihalogenations. Science. 2021;371(6528):507-514. doi:10.1126/science.abf2974
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