Method for preparing sulfamide as intermediate of sulfonylurea herbicide
A technology of sulfonamides and sulfonylureas, applied in the field of fine chemistry, can solve the problems of low yield and many operation steps, and achieve the effect of improving yield and avoiding hydrolysis
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Embodiment 1
[0028] Embodiment 1: Synthesis of 4-ethoxycarbonyl-1-acetylpyrazole-5-sulfonamide
[0029] Weigh 21.4g of 4-ethoxycarbonyl-1-acetylpyrazole-5-thiol into the reactor, add 150g of water, then add about 25mL of concentrated hydrochloric acid, ice-bath to -5°C, and slowly introduce chlorine gas, A large amount of white solids appeared in the reactor, which was confirmed by liquid chromatography analysis until there was no raw material peak, then 200mL of chloroform was added, stirred to dissolve the white solids, and the liquids were separated. After the organic phase was dried over anhydrous magnesium sulfate, it was cooled to 0°C. Ammonia gas was introduced slowly until the pH of the final reactant reached alkaline (about 9). After filtration, a white solid was obtained, which was washed with tap water to obtain 22.7 g of a white solid of 4-ethoxycarbonyl-1-acetylpyrazole-5-sulfonamide with a content of 98%.
Embodiment 2
[0030] Example 2: Synthesis of 3-chloro-5-trifluoromethoxypyridine-2-sulfonamide
[0031] Weigh 27.1g of 3-chloro-5-trifluoromethoxypyridine-2-thiol, put it into a reaction bottle, add 150mL of water, then add 40mL of glacial acetic acid, ice-bath to 0°C, and slowly introduce chlorine gas to maintain The reaction temperature does not exceed 10°C. Continuously take samples and detect in the middle until the peak of the reactant disappears. Pour the reaction solution into the ice-water mixture, add trichloroethane to shake and extract, and the extract is cooled and dried by anhydrous magnesium sulfate. To 0 ℃, slowly through the ammonia gas. Until the reaction solution reaches alkalinity (about 9), the following operations are the same as in Example 1 to finally obtain 30.3 g of 3-chloro-5-trifluoromethoxypyridine-2-sulfonamide with a purity of 95.2%.
Embodiment 3
[0032] Example 3: Synthesis of 4-sulfonyl ethyl ester-1-methylimidazole-5-sulfonamide
[0033] Weigh 26.1g of 4-sulfonyl ethyl ester-1-methylimidazole-5-mercaptan, put it into a reaction flask, add 150mL of water, slowly add 20mL of concentrated sulfuric acid, cool in an ice bath until the temperature is -5°C, and perform the remaining operations As in Example 1, 27.8 g of 4-sulfonyl ethyl ester-1-methylimidazole-5-sulfonamide was finally obtained with a purity of 95.7%.
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