Hexachloroethane → 2,3-Dichloro-4-fluorobenzoic acid

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Reaction Steps

sBuLi (97 mL, 126 mmol) was dissolved in tetrahydrofuran (THF) (200 mL) at −78° C. and TMEDA (19.02 mL, 126 mmol) was added. 3-chloro-4-fluorobenzoic acid (10 g, 57.3 mmol, commercially available from e.g. Sigma-Aldrich, Fluorochem or Apollo) dissolved in tetrahydrofuran (THF) (50 mL) was added dropwise at −78° C. and the solution stirred at this temperature for 30 minutes. Hexachloroethane (54.2 g, 229 mmol) dissolved in tetrahydrofuran (THF) (200 mL) was added dropwise and the solution stirred to room temperature over 4 hours. Water (25 mL) was added and the solution concentrated in vacuo. The residue was partitioned between diethyl ether (300 mL) and saturated sodium bicarbonate solution (50 mL) and extracted with saturated sodium bicarbonate solution (3×50 mL). The aqueous phase was acidified to pH1 with 5N hydrochloric acid, extracted with diethyl ether (3×200 mL), combined extracts dried over anhydrous magnesium sulfate and concentrated in vacuo to afford a crude solid (9.21 g). The crude solid was recrystalised from heptane/diethyl ether to afford the desired product in 4.91 g.

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