Synthesis conditions and activity of various Lewis acids for the fluorination of trichloromethoxy-benzene by HF in liquid phase

A General Approach to (Trifluoromethoxy)pyridines: First X‐ray Structure Determinations and Quantum Chemistry Studies

“…The chlorine/fluorine exchange proceeds rapidly to the OCF 2 Cl intermediate. [11] However, the final Cl/F exchange is the rate-determining step, as had also previously been observed in the aromatic series for the conversion of -CCl 3 into -CF 3 . Under optimized reaction conditions, SbCl 5 (0.15 equiv.)…”

6.06 Synthesis of Fluorides

“…87 SF 4 was used later to exhaustively fluorinate the carboxy group of benzoic acids to afford trifluoromethylated arenes. 88 Similarly, aryl trichloromethyl ethers have been fluorinated with hydrogen fluoride, 89 SbF 5 , 90 SbF 3 in the presence of SbF 5 , 91 and molybdenum hexafluoride, 92 with the trichloromethyl ether being synthesized in situ 89b or before the reaction by chlorination of the aryl methyl ether. 91a,93 Aryl chlorothionoformates 91c,92a can also be used as precursors to trifluoromethyl ethers.…”

Lability of the trifluoromethyl group of trifluoromethoxybenzenes under HF/Lewis acid conditions

“…CF 3 lability under HF/Lewis acid conditions was not anticipated while choosing CF 3 O-Ph as an auxiliary solvent as CF 3 O-Ph had been reported to be stable to Friedel-Crafts alkylation (in the presence of BF 3 as Lewis acid) [8][9][10] and was most certainly synthesized with HF and often, Lewis acid catalysts [11][12][13][14][15][16]! A closer look at the literature on the synthesis of trifluoromethoxybenzenes disclosed some interesting points.…”