4-Iodoimidazole synthesis

Yield:71759-89-2 70.2%

Reaction Conditions:

with iodine;sodium iodide;sodium hydroxide in water at 0 - 20; for 6 h;Time;

Steps:

1; 2 Example 1
Sodium hydroxide (24.0 g, 0.60 mol) was dissolved in 150 mL of water, the temperature was lowered to room temperature, then imidazole (40.8 g, 0.60 mol) was added, and dissolved with stirring.Sodium iodide (33.8 g, 0.23 mol) was dissolved in 45 mL of water, the temperature was lowered to room temperature, and then iodine (38.1 g, 0.15 mol) was added.An aqueous solution of iodine and sodium iodide was added dropwise to an aqueous solution of sodium hydroxide and imidazole at 0 ° C. After the addition was completed, the reaction was carried out at 0 ° C for 6 hours.After the reaction was completed, the pH was adjusted to 7-8 with concentrated hydrochloric acid, a solid was precipitated, and suction-dried to obtain 17.1 g of white solid.The filtrate was added with 50 g of sodium chloride to saturation, and extracted with ethyl acetate 300 mL × 2,The organic layers were combined and concentrated to dryness under reduced pressure to obtain 19 g of light yellow solid.19 g of light yellow solid was recrystallized with a mixed solvent containing 20 mL of ethyl acetate and 20 mL of n-hexane,Suction filtration and drying gave 9.5 g of white solid, which was the recovered raw material imidazole.The mother liquor was concentrated under reduced pressure to obtain 9.1 g of white solid,Combined with 17.1 g of white solid precipitated after the reaction was completed and neutralized, it was crude 4-iodo-1H-imidazole.The combined 26.2 g of solid was added to a mixed solvent containing 120 mL of water and 4 mL of ethanol, heated to reflux for 1 hour, and filtered while hot.The resulting filter cake was 4,5-diiodo-1H-imidazole.The filtrate was cooled to room temperature and crystallized, and suction filtration was performed to obtain 24.7 g of white solid.This white solid was recrystallized from a mixed solvent containing 24 mL of isopropanol and 12 mL of n-hexane,18.4 g of white crystals were obtained, which was pure 4-iodo-1H-imidazole with a total yield of 70.2%.

References:

China Pharmaceutical University;Sun Haiying;Fang Kunsen;Ma Zonghui;Li Lianwei CN110938036, 2020, A Location in patent:Paragraph 0021-0026

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