Scientists in South Korea have shown how to convert a simulant of a chemical warfare agent into a common drug.

Chemical warfare agents are inherently toxic and aim to injure, deactivate, and kill. Despite international conventions that severely limit their distribution, high inventories carry the risk of deliberate or accidental release and disposal is not easy.

“The methods commonly used to neutralize organophosphonate active ingredients are incineration and alkaline hydrolysis,” says Se-Jun Yim, a researcher at Pohang University of Science and Technology, who points out secondary contamination problems such as air pollution and hazardous waste dumping. . Although alternative methods can cleanly capture and neutralize these active ingredients, the batch processes involved are impractical and inefficient and only feasible for milligram quantities.

Now Yim and his colleagues have developed a new device to quickly and efficiently break down a toxic neurotoxin simulant – dimethyl-4-nitrophenyl phosphate, commonly known as paraoxon. And instead of hazardous waste, the device has a useful power, namely the active pharmaceutical ingredient paracetamol.

“Enabling us to recycle the waste generated during the process is the main goal of this work – to convert waste into a product that adds value,” says Yim.

A scheme showing an influencing process to neutralize paraoxon for the production of paracetamol in a microreactor

The Teflon microreactor works according to a flow process and not a batch process, which means that Paraoxon can be fed seamlessly through the system. Reagents are added as the reaction goes through three stages: degradation of paraoxon to p-Nitrophenol, reduction on p-Aminophenol and finally the synthesis of paracetamol by acetylation. The reactor is portable, the size of a suitcase and can neutralize 700 grams of Paraoxon per day.

“It is a very efficient process with the highest space-time yield,” says Julien Legros, whose group at the University of Rouen Normandy, France, is also developing flow reactors to neutralize chemical warfare agents. However, he notes that paracetamol as an end product is very specific to paraoxon as a starting material, and paraoxon, in turn, is of limited importance in chemical warfare. “Although paraoxon can be used as a chemical warfare simulant, in practice it is mainly used as a pesticide and is not intended for military use,” he says.

Yim, who used Paraoxon in the study because of its relative safety and availability for laboratory use, agrees that making value-added products from stronger chemical warfare agents remains a challenge. “Soman, sarin and tabun produce fluoride and cyanide ions during hydrolysis and are not suitable for the production of active pharmaceutical ingredients,” he says.

Legros adds, “It’s still nice to be able to do something peaceful and synthesize a pharmaceutical ingredient from a toxic pesticide.”

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