P-08 - Surfaces and Interfaces

HF-loaded Aluminium chlorofluoride as a nanoscopic solid acid catalyst for hydrofluorination reactions

Maeva-Charlotte KERVAREC and Thomas BRAUN

Institut für Chemie, Humboldt-Universität zu Berlin, Brook-Taylor-Straße 2, 12489, BERLIN, GER

Aluminum chlorofluoride 1, ($\ce{AlClxF3-x}$, x=0.05-0.25) is an amorphous microporous Lewis acid with a highly distorted structure and large surface area (>200m2g-1). This catalyst exhibits an extraordinary acid strength due to the Chlorine atoms present in the structure and was patented by DuPont in 1992 2. It reaches the acidity of antimony pentafluoride, $\ce{SbF5}$, and shows reactivity towards C-F/C-Cl bond activations, H/D exchange reactions, and hydroarylation of olefins as well as Friedel-Craft type reaction. 3 4 The incorporation of fluorinated groups into organic compounds can improve their properties compared to the nonfluorinated ones. Two possibilities to synthesize them are either to use available fluorinated compounds and derivatize them or to incorporate fluorinated group using fluorinating reagents. The catalytic activity of ACF was tested for both pathways, and the interaction of HF with the surface of ACF (HF-loaded-ACF) was studied using different characterization methods, such as MAS NMR spectroscopy, FTIR-ATR, TGA, and NH3-TPD. Furthermore, the reactivity of this new material was investigated towards different alkynes.

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Possible interactions of HF with the surface of the catalyst

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  2. C. G. Krespan, Process for Production of Polyfluoroolefins, US5162594A (1991), US5162594A

  3. T. Braun et.al., Angew. Chem. Int. Ed (2017), 56, 16338-16341

  4. T. Braun et.al., ChemCatChem (2016), 8, 1945-1950