Eco-friendly chlorine method could transform drug and chemical production

Chlorine plays an essential part in daily life, from keeping pools clean to preserving food. Now, a team of chemists at Rice University has developed a more environmentally friendly way to integrate chlorine into chemical building blocks for medications, plastics, pesticides and other essential products while reducing costs. This research was published in Nature Synthesis on Jan. 2.

Led by Julian West, assistant professor of chemistry and a Cancer Prevention and Research Institute of Texas (CPRIT) Scholar, the research team developed a photocatalytic process that uses iron and sulfur catalysts activated by mild blue light to add chlorine atoms to organic molecules. This innovation eliminates the need for harsh chemicals or high temperatures typically required in chlorination, which can generate difficult-to-purify byproducts.

“Our method uses sustainable, low-cost catalysts and operates at room temperature with gentle blue light,” West said. “It provides a targeted, efficient way to chlorinate molecules without conventional approaches’ environmental and purification challenges.”

One advantage of the team’s method is its precise targeting of chlorine placement on molecules, a process called anti-Markovnikov hydrochlorination. This precision creates highly pure products by selectively attaching chlorine atoms to less-reactive parts of the starting molecules. With this approach, chemists can avoid extra purification steps that are often time-consuming and costly.

The researchers also unveiled a novel addition to this process: using heavy water to incorporate deuterium, a stable hydrogen isotope. This step could make certain drugs last longer in the body by increasing their stability, potentially enhancing their effectiveness.

“It’s exciting that this method could open new doors for modifying pharmaceuticals and natural products in ways that weren’t possible with older techniques,” West said.

Research collaborators include Rice students Kang-Jie Bian, Shih-Chieh Kao, Ying Chen, Yen-Chu Lu, David Nemoto Jr. and Xiaowei Chen. Angel Martí, professor and chair of chemistry and professor of bioengineering and materials science and nanoengineering, also contributed to this study.