A fluorolytic solgel route to access an amorphous Zr fluoride catalyst: a useful tool for C-F bond activation

A route to a ZrF 4 catalyst active in room temperature Friedel-Crafts and dehydrofluorination reactions was developed via a fluorolytic sol-gel route, which was followed by a postfluorination step using a stream of CHClF 2 . The behaviour of different Zr( iv ) precursors in a sol-gel reaction with anhydrous isopropanol/HF solution was investigated. The subsequent post-fluorination step was optimised in its temperature ramp and confirmed the necessity of a fluorination of the generated xerogels to obtain catalytic activity. The process is discussed in the context of the analysis of the materials using Brunauer-Emmett-Teller analysis (BET), powder X-ray diffraction (XRD), infrared spectroscopy (IR), thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC). The local structure of the amorphous catalyst was elucidated by extended X-ray absorption fine structure spectroscopy (EXAFS). A route to a ZrF 4 catalyst active in room temperature Friedel-Crafts and dehydrofluorination reactions was developed via a fluorolytic sol-gel route, which was followed by a postfluorination step using CHClF 2 .