A kind of preparation method of 1-methyl-1h-1,2,4-triazole-3-carboxylic acid methyl ester
A technology of methyl formate and aminotriazole, applied in the direction of organic chemistry, can solve the problems of unfavorable industrial production, volatile methyl iodide, toxic price, etc., and achieve the effect of low production cost, easy availability of raw materials, and cheap price
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Embodiment 1
[0028]
[0029] Under nitrogen protection, oxalic acid dihydrate (63g, 0.5mol) was added into water (120mL); the temperature was raised to 80-85°C to dissolve, and aminoguanidine bicarbonate (44.9g, 0.33mol) was added in batches. Raise the temperature to 98-100°C to react for 5 hours, lower the temperature to 50-60°C, and then add 30% NaOH aqueous solution to adjust the pH=11-12. Then it was warmed to reflux for 1 hour, cooled to room temperature and adjusted to pH=3-4 with concentrated hydrochloric acid. Filter and rinse the filter cake with water and cold methanol. 40.45 g of 3-aminotriazole-5-carboxylic acid was obtained, yield 95.7%, HPLC 99.3%.
[0030] Synthesis of 1,2,4-triazole-3-carboxylic acid
Embodiment 2
[0032]
[0033] Under the protection of nitrogen, mix 3-aminotriazole-5-carboxylic acid (38.4g, 0.3mol) and acetonitrile (40mL), cool down to 0°C, add 126g of 45% hydrobromic acid and stir to dissolve -2~2 Add at ℃ and then slowly dropwise add a solution containing sodium nitrite (22.1g, 0.32mol) dissolved in 31mL of water, after the dropwise addition, stir for 2 hours, then add a methanol solution containing hypophosphorous acid (40g). After 4 hours of reaction, the color gradually changed from orange to colorless. Slowly raise the temperature to 25-35°C and react for 3 hours. The layers were separated, and the aqueous layer was extracted with ethyl acetate. The organic phases were combined and washed with sodium bicarbonate and saturated brine. The organic phase was concentrated to no liquid, 30% aqueous methanol was added to make a slurry, and 26.5 g of 1,2,4-triazole-3-carboxylic acid was obtained by filtration, with a yield of 78.1%, and HPLC of 97.9%. m / z=114.0470[...
Embodiment 3
[0035]
[0036] Under the protection of nitrogen, mix 3-aminotriazole-5-carboxylic acid (38.4g, 0.3mol) and acetonitrile (40mL), cool down to 0°C, add 90.5g of 65% sulfuric acid and stir to dissolve -2~2°C Add and then slowly add dropwise a solution containing sodium nitrite (22.1g, 0.32mol) dissolved in 31mL of water, and then stir for 2 hours after the dropwise addition, then add sodium hypophosphite (56g) and 30mL of ethanol. After 3 hours of reaction, the color gradually changed from orange to colorless. Slowly raise the temperature to 25-35°C and continue the reaction for 5 hours. The layers were separated, and the aqueous layer was extracted with ethyl acetate. The organic phases were combined and washed with sodium bicarbonate and saturated brine. The organic phase was concentrated to stagnant liquid, 30% methanol aqueous solution was added to make a slurry, and 27.5 g of 1,2,4-triazole-3-carboxylic acid was obtained by filtration, the yield was 81.2%, and the HPLC...
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