Method for preparing 2-nitroimidazole
A technology of nitroimidazole and aminoimidazole is applied in the field of synthesis of 2-nitroimidazole, can solve the problems of large amount of catalyst 4-lutidine, low extraction efficiency, long extraction time and the like, and achieves shortening extraction time, The effect of saving extraction solvent and improving reaction yield
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Embodiment 1
[0024] Example 1. Add 15g of 2-aminoimidazole sulfate, 100mL of water and 100mL of 40wt% fluoboric acid in a flask, and add dropwise 100mL of aqueous solution containing 40g of sodium nitrite after cooling to about -3°C, and drop it in about 45 minutes. Stir at 0°C for 1 hour after completion, then pour into 1.5L water containing 200g of copper sulfate pentahydrate and 2g of bipyridine, add 40g of sodium nitrite while stirring, stir at room temperature for 3 hours after addition, then add concentrated hydrochloric acid Adjust the pH to 2, extract with ethyl acetate for 12 hours in a liquid-liquid extraction device, and then concentrate the extract to 1 / 4 of the total volume. After standing and cooling, 10.3 g of light yellow crystals are precipitated. The yield is 80%, and the mother liquor is reserved for the next step. For one extraction.
Embodiment 2
[0025] Example 2. Add 15g of 2-aminoimidazole sulfate, 100mL of water and 100mL of 40% fluoroboric acid in the flask, and add dropwise 100mL of aqueous solution containing 40g of sodium nitrite after cooling to about -3°C. After about 45 minutes, add Stir at 0°C for 1 hour after completion, then pour into 1.5L water containing 200g of copper sulfate pentahydrate and 2g of bipyridine, add 40g of sodium nitrite while stirring, stir at room temperature for 3 hours after addition, then add concentrated hydrochloric acid Adjust the pH to 2, extract with ethyl acetate for 12 hours in a liquid-liquid extraction device, use the mother liquor recovered in the previous example for part of the extract, concentrate the extract to 1 / 4 of the total volume after extraction, and let it stand for cooling 11.0 g of pale yellow crystals were precipitated, with a yield of 86%.
Embodiment 3
[0030] Example 3. Add 15g of 2-aminoimidazole sulfate, 100mL of water and 100mL of 40% fluoboric acid in the flask, and add dropwise 100mL of aqueous solution containing 40g of sodium nitrite after cooling to about -3°C, and drop it in about 45 minutes. Stir at 5°C for 1 hour after completion, then pour into 1.5L water containing 200g of copper sulfate pentahydrate and 2g of bipyridine, add 40g of sodium nitrite while stirring, stir at room temperature for 3 hours after addition, and then add concentrated hydrochloric acid Adjust the pH to 2, evaporate half of the water under reduced pressure, and then extract with ethyl acetate for 12 hours in a liquid-liquid extraction device. Part of the extract is recovered in the previous example. After extraction, the extract is concentrated to the total volume 1 / 4 of the product, 10.9 g of light yellow crystals were precipitated after standing and cooling, with a yield of 85%.
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