4-(4-Fluorophenoxy)benzoic acid

1765-93-1

99-76-3

129623-61-6

To a round bottom flask containing 4-fluorophenylboronic acid (2.1 g, 15 mmol), copper(II) acetate (1.4 g, 7.5 mmol), activated powdered molecular sieves (ca. 2 g), and nipagin methyl ester (1.2 g, 7.5 mmol) was added triethylamine (5.2 mL, 38 mmol) followed by dichloromethane (75 mL). The reaction mixture was stirred at room temperature for 16 hours while air was continuously passed through. Upon completion of the reaction, the reaction mixture was diluted with dichloromethane and filtered through a silica gel column. The silica gel was washed with a solvent mixture of ethyl acetate-heptane. The filtrate was concentrated under reduced pressure and subsequently dissolved in 1,4-dioxane (15 mL). To this solution was added aqueous lithium hydroxide (1 N, 15 mL) and stirred at room temperature for 18 hours. At the end of the reaction, the pH of the reaction mixture was adjusted to acidic (pH < 6) with aqueous hydrochloric acid (1 N). The resulting precipitate was collected by filtration, washed with water and dried under vacuum to afford 4-(4-fluorophenoxy)benzoic acid (1.6 g, 90% yield). Mass spectrometry analysis (ESI) showed the (M-H)- peak of C13H9FO3 at m/z 231.