The preparation of fluoroarenes by the catalytic decarboxylation of aryl fluoroformates

The catalytic decarboxylation of phenyl fluoroformate to fluorobenzene has been achieved with yields of 70–80% in a flow system using alumina or alumina-based catalysts. The reaction occurs in short space times (<1 s) and with optimal efficiency at ca. 300 °C (some 500 °C lower than the temperature required for the thermal decomposition of the fluoroformate). Impregnation of the alumina with a platinum group metal gave the following order of catalytic activity; Pt/Al₂O₃>Pd/Al₂O₃>Rh/Al₂O₃≈Al₂O ₃.2,4,6-Trimethlyphenyl flouroformate, a new material, was found to decarboxylate similarly to give 1-flouro-2,4,6-trimethylbenzene, but 4-chlorophenyl flouroformate was noted to produce only low yields (～10%) of the corresponding arly flouride