The general procedure for the synthesis of 2-bromo-3-hydroxybenzaldehyde from m-hydroxybenzaldehyde was as follows: 3-hydroxybenzaldehyde (5 g, 0.04 mol), iron powder (172 mg, 3 mmol), and sodium acetate (6.72 g, 0.08 mol) were suspended in acetic acid (40 mL), warmed until a clarified solution was formed, and subsequently cooled to room temperature. A glacial acetic acid solution of bromine (10 mL) was slowly added dropwise to the mixture over 15 minutes. After the dropwise addition was completed, stirring of the reaction mixture was continued for 2 hours. Upon completion of the reaction, the mixture was poured into ice water and extracted with dichloromethane (3 x 50 mL). The organic phases were combined, dried over anhydrous Na2SO4 and concentrated. The residue was recrystallized by dichloromethane to afford the target product 2-bromo-3-hydroxybenzaldehyde (2.3 g, 28% yield). The product was characterized by 1H NMR (400 MHz, DMSO-d6): δ 10.30 (s, 1H), 7.54-7.51 (m, 1H), 7.39-7.35 (m, 1H), 7.31-7.27 (m, 1H), 5.90 (s, 1H).
