The general procedure for the synthesis of 4-iodophthalic acid from 3,4-dimethyl iodobenzene was as follows: 3,4-dimethyl iodobenzene (31 mL, 0.22 mol) was co-dissolved with pyridine (125 mL) in water (375 mL), and potassium permanganate (205 g, 1.3 mol) was slowly added at 60°C and reacted for 16 h under continuous stirring. After completion of the reaction, the temperature was maintained at 60°C and the filtrate was filtered through diatomaceous earth to remove solid impurities. After cooling the filtrate to room temperature, it was acidified by adjusting the pH to 2 with 6N hydrochloric acid and subsequently extracted with ethyl acetate. After purification by column chromatography, the target product 4-iodophthalic acid (44 g, 69% yield) was concentrated.
