Amorphous Lewis-acidic zirconium chloro fluoride as a catalyst for heterogeneous C-F Bond activation and HF transfer reactions of fluoroalkanes Christian Heinekamp 1[a,b] , Ana Guilherme Buzanich [a] , Thomas Braun* [b] ,Franziska Emmerling* [a,b] 1 Bundesanstalt fuer Materialforschung und pruefung, Germany, [a] Department Materials Chemistry, Federal Institute for Material Research and Testing, Berlin, Germany, [b] Department of Chemistry, Humboldt Universität zu Berlin, Berlin, Germany In recent years, fluorine chemistry has gained increasing political attention. Owing to a growing shortage of fluorspar, a raw material used for producing fluorinated base chemicals, fluorospar has been named among the 30 critical raw materials in the EU. [2] As such, it becomes increasingly important to recycle existing fluorinated compounds and make them available as sources of fluorine for reactions. Significant progress has been made in the field of C-F bond activation using heterogeneous catalysts such as aluminum chloro fluoride (ACF). [3] However, the transfer of fluorine atoms from one molecule to another using heterogeneous catalysts has not yet been reported. In this study, we successfully synthesized amorphous zirconium chloro fluoride (ZCF), which exhibits medium lewis acidity. In addition to investigating the local coordination sphere around the Zr atoms and the material properties, we were able to establish a catalytic behavior of ZCF in C-F bond activation reactions. We present a heterogeneous catalyst that performs dehydrofluorination of a fluoroalkane and consecutive hydrofluorination of an alkyne at room temperature.
Scheme 1 : a) Schematic representation of the coordination sphere of Zr in zirconium chloro fluoride determined by X-ray absorption spectroscopy b) reaction scheme for the catalytic HF transfer from fluoropentane to alkynes. References
1. C. Heinekamp, A. Guilherme Buzanich, T. Braun, F. Emmerling, manuscript in work 2023 . 2. S. Bobba, S. Carrara, J. Huisman, F. Mathieux, C. Pavel, European Commission 2020 , 100.
3. a) M. Ahrens, G. Scholz, T. Braun, E. Kemnitz, Angew Chem Int Ed Engl 2013 , 52 , 5328-5332; b) G. Meißner, D. Dirican, C. Jäger, T. Braun, E. Kemnitz, Catalysis Science &Technology 2017 , 7 , 3348-3354; c) M.-C. Kervarec, E. Kemnitz, G. Scholz, S. Rudić, T. Braun, C. Jäger, A. A. L. Michalchuk, F. Emmerling, Chemistry – A European Journal 2020 , 26 , 7314-7322.
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