Fluorochemicals from fluorspar via a phosphate-enabled mechanochemical process that bypasses HF

All fluorochemicals—including elemental fluorine and nucleophilic, electrophilic, and radical fluorinating reagents—are prepared from hydrogen fluoride (HF). This highly toxic and corrosive gas is produced by the reaction of acid-grade fluorspar (>97% CaF2) with sulfuric acid under harsh conditions. The use of fluorspar to produce fluorochemicals via a process that bypasses HF is highly desirable but remains an unsolved problem because of the prohibitive insolubility of CaF2. Inspired by calcium phosphate biomineralization, we herein disclose a protocol of treating acid-grade fluorspar with dipotassium hydrogen phosphate (K2HPO4) under mechanochemical conditions. The process affords a solid composed of crystalline K3(HPO4)F and K2−xCay(PO3F)a(PO4)b, which is found suitable for forging sulfur-fluorine and carbon-fluorine bonds. Description Editor’s summary Fluorine occurs naturally as a calcium salt in the highly insoluble mineral fluorspar. For well over 200 years, the first step in accessing fluorinating reagents has been the conversion of fluorspar to perilously toxic and corrosive hydrofluoric acid (HF). Patel et al. now report a safer alternative means of activating fluorspar for downstream fluorination chemistry. Specifically, they enhanced its solubility by grinding it in a ball mill with dipotassium hydrogen phosphate salt. The resultant solid can then be used to form carbon–fluorine and sulfur–fluorine bonds with electrophilic reactants in an alcohol solvent. —Jake S. Yeston A versatile inorganic fluorinating reagent is prepared by mechanochemical activation of fluorspar with a phosphate salt.