An amorphous Lewis-acidic zirconium chlorofluoride as HF shuttle: C–F bond activation and formation

Abstract

A process to shuttle HF from a fluoroalkane to alkynes has been developed. The consecutive dehydrofluorination and hydrofluorination steps are catalysed by an amorphous zirconium chlorofluoride at room temperature.

Catalytic HF Shuttling between Fluoroalkanes and Alkynes**

“…Very recently, BF 3 ⋅ OEt 2 has been reported as a catalyst for the homologation of fluoroalkanes with diazoesters, [29] and the intramolecular fluorocarbamoylation of alkynes [30] . Upon revision of this work, [31] a Lewis‐acidic heterogeneous catalyst was reported for HF shuttling between fluoroalkanes and alkynes [32] …”

“…[30] Upon revision of this work, [31] a Lewis-acidic heterogeneous catalyst was reported for HF shuttling between fluoroalkanes and alkynes. [32] Initially, a series of group 13 Lewis acid catalysts and group 15/16 bases were screened for the reaction of 1fluorohexane with a small array of alkynes. BF 3 • OEt 2 in combination with weak Lewis-bases such as 2,6-dichloropyridine or triphenylphosphine proved active for HF shuttling in modest yields.…”

A fluorolytic sol–gel route to access an amorphous Zr fluoride catalyst: a useful tool for C–F bond activation

“…20 ZCF has recently been reported as the first heterogeneous HF shuttle at room temperature. 21 Despite this knowledge, and the fact that zirconium oxide is described as a stronger Lewis acid than other metal oxides, 22 zirconium fluoride-based materials and catalysts have only recently been reported or investigated. Zirconium fluoride has been described as having Lewis-acidic properties similar to the metastable β-AlF 3 phase.…”