The general procedure for the synthesis of 5-iodo-2-methyl-1H-imidazole from 4,5-diiodo-2-methyl-1H-imidazole was as follows: 4,5-diiodo-2-methyl-1H-imidazole (8.5 g, 25.5 mmol) was dissolved in 430 mL of a 3:7 (v/v) solvent mixture of ethanol and water. Sodium sulfite (25.7 g, 204 mmol) was added to the solution and the reaction mixture was heated to reflux (about 100 °C) for 24 hours. Upon completion of the reaction, the reaction mixture was concentrated to about half of the original volume. The precipitated solid was filtered and washed with cold water to give a final 5.3 g (66% yield) of 5-iodo-2-methyl-1H-imidazole. The product was analyzed by mass spectrometry to confirm that the m/z of the molecular ion peak (M + H)+ was 209.
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