Synthesis of 3,4-dibromomaleic anhydride: A mixture of maleic anhydride (2.0 g, 20.39 mmol), aluminum chloride (40.8 mg, 0.3 mmol), and bromine (2.1 mL, 40.78 mmol) was placed in a sealed tube and heated to react for 16 hr at 120 °C. After completion of the reaction, it was cooled to room temperature and the reaction mixture was transferred to ethyl acetate. The ethyl acetate solution was filtered and the filtrate was subsequently evaporated. To the resulting red solid, 100 mL of chloroform was added and the filtrate was filtered and evaporated to give an off-white to yellow solid in 87% yield.13C NMR (CDCl3) data (ppm): 131.8, 159.0.
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