General procedure for the synthesis of 1-fluorocyclopropanecarboxylic acid from 1-fluorocyclopropylmethyl ketone: Bromine (14.8 g, 93 mmol) was slowly added to a solution of sodium hydroxide (12.36 g, 300 mmol) in water (50 mL) at below 10 °C. Subsequently, 1-(1-fluorocyclopropyl)ethanone (3.3 g, 30 mmol) was added. The reaction mixture was slowly cooled to below 0°C and then stirred at room temperature for 1 hour. Sodium metabisulfite was added until the solution became colorless. Ethyl acetate (50 mL) was added, and the aqueous phase was separated and acidified with hydrochloric acid (2 M) to pH 2. The aqueous phase was extracted with ethyl acetate (3 x 50 mL). The organic phases were combined, dried over anhydrous sodium sulfate and concentrated to give 1-fluorocyclopropanecarboxylic acid as a white solid (2.2 g, 66% yield).1H NMR (CDCl3, 400 MHz): δ 1.49-1.45 (m, 4H).
