image: Potassium fluoride(KF) undergoes cation exchange reaction with SO3H group of Amberlyst 15DRY, leading to the quantitative production of hydrogen fluoride. Further reaction with amines leads to the formation of multiple amine-3HF complexes—a range of new fluorinating reagents.
Credit: Professor Toshiki Tajima from Shibaura Institute of Technology, Japan
Fluorine-based compounds are everywhere—from life-saving pharmaceuticals and crop protection agents to high-performance materials like Teflon and refrigerants. Thanks to their unique chemical properties, which make them indispensable across various industries. But synthesizing these compounds has long been a challenge due to the hazardous and toxic fluorinating reagents.
Hydrogen fluoride (HF) is one such reagent that is effective and inexpensive, but its high toxicity and corrosive nature make it extremely difficult to handle. In a recent breakthrough, researchers led by Professor Toshiki Tajima from Shibaura Institute of Technology, Japan, have developed a groundbreaking method to safely and efficiently generate HF from simple and stable materials—unlocking a safer path to fluorination chemistry. The study, made available online on April 22, 2025, and was published in Volume 31, Issue 32 of the journal Chemistry – A European Journal on June 6, 2025, unveils a cation exchange method to safely generate HF on demand.
Cation exchange reactions are chemical processes where positively charged ions are swapped between a solid porous material (usually a resin) and a salt solution. In the current study, the researchers used Amberlyst 15DRY, a commercially available solid acid resin, as the cation exchange resin and potassium fluoride (KF) which is a stable and inexpensive salt. By combining these solids in acetonitrile, they triggered a cation exchange reaction, which resulted in the quantitative production of HF without any external hazards.
“In a single step of the cation exchange reaction, we only generated 69% of HF from KF. But by removing the HF after each run and repeating the reaction seven times, we achieved nearly complete HF production from KF conversion,” explains Prof. Tajima.
Once the reaction was complete, HF was separated from the resin, and organic amines were added to the HF solution in a 1:3 ratio. HF was immediately captured by these organic amines to form stable amine-3HF complexes. The complexes were then isolated by evaporating the solvent under reduced pressure. Amine-3HF complexes commonly act as nucleophilic fluorinating agents, i.e.; these complexes donate fluoride ions (F⁻) to other molecules while replacing another negatively charged leaving group (nucleophile) from those molecules.
These fluorination reactions are especially valuable for various applications in industries.
“Various HF complexes can be derived from HF,” notes Prof. Tajima. “These complexes act as fluorinating agents and could enable the synthesis of novel pharmaceuticals, functional materials, and even molecular probes.”
What sets this study apart is that it eliminates the use of pressurized HF gas and corrosive liquid reagents, making the process safer and more aligned with green chemistry principles. Also, the method operates under ambient conditions with common laboratory reagents without the use of any special equipment, making it suitable for both laboratory and industrial scales. Moreover, the resin used for the cation exchange reaction was effectively reused for almost over 10 times, marking the efficiency and sustainability of the approach.
The study marks a significant milestone in fluorination chemistry, opening avenues for multiple applications across various industries. The new fluorinating agents generated through the complexation could open multiple avenues for unique applications in pharmaceuticals, agrochemicals, and material sciences, all while ensuring a simpler, safer, and sustainable process of fluorination.
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Reference
DOI: 10.1002/chem.202500789
About Shibaura Institute of Technology (SIT), Japan
Shibaura Institute of Technology (SIT) is a private university with campuses in Tokyo and Saitama. Since the establishment of its predecessor, Tokyo Higher School of Industry and Commerce, in 1927, it has maintained “learning through practice” as its philosophy in the education of engineers. SIT was the only private science and engineering university selected for the Top Global University Project sponsored by the Ministry of Education, Culture, Sports, Science and Technology and had received support from the ministry for 10 years starting from the 2014 academic year. Its motto, “Nurturing engineers who learn from society and contribute to society,” reflects its mission of fostering scientists and engineers who can contribute to the sustainable growth of the world by exposing their over 9,500 students to culturally diverse environments, where they learn to cope, collaborate, and relate with fellow students from around the world.
Website: https://www.shibaura-it.ac.jp/en/
About Professor Toshiki Tajima from SIT, Japan
Dr. Toshiki Tajima is a Professor at the College of Engineering, Shibaura Institute of Technology, Japan. He earned his doctorate from the Interdisciplinary Graduate School of Science and Engineering, Tokyo Institute of Technology, and specializes in organic electrochemistry and synthesis. He has over 56 peer-reviewed publications and over 11 book chapters to his credit. His research mainly focuses on nanotechnology, green chemistry, environmental chemistry, and sustainable sciences.
Funding Information
This work was supported by JSPS KAKENHI Grant Numbers JP19K05567 and JP22K05197.
Journal
Chemistry - A European Journal
Method of Research
Experimental study
Subject of Research
Not applicable
Article Title
Quantitative Generation of HF from KF and Formation of Amine-3HF Complexes by Using Cation Exchange Reaction Between KF and Amberlyst 15DRY
Article Publication Date
6-Jun-2025