Method for preparing D, L-pantolactone through normal-pressure reduction
A technology of pantotolactone and pantoacid, which is applied in the field of preparation of D,L-pantotolactone, can solve problems such as high-risk processes and potential safety hazards, and achieve easy production operations, low production costs, and simple processes Effect
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Embodiment 1
[0028] Add 74g (0.5 moles) of 50% glyoxylic acid to a 500ml three-necked bottle, cool down the cooling device to 15°C, and slowly add 53.12g (0.525 moles) of triethylamine, after the addition of triethylamine, stir the reaction at 25°C For 30 minutes, add 39.6g (0.55 moles) of isobutyraldehyde, raise the temperature to 70°C for 6 hours, cool down to 15°C, slowly add 27g (0.5 moles) of potassium borohydride, after the addition is complete, react for 4 hours, slowly add Add 70% sulfuric acid until the pH of the feed solution is 1.25, raise the temperature to 87°C and react for 4 hours, cool down to 15°C with the cooling device, adjust the pH of the feed solution to 7.5 with ammonia water, extract with dichloroethane, 300ml each time, combine the organic layers, The solvent was recovered by distillation, and 64 g of D,L-pantolactone was obtained by distillation under reduced pressure, with a product yield of 98.5% and a purity of 99.16%.
Embodiment 2
[0030] Add 92.5g (0.5 moles) of 40% glyoxylic acid to a 500ml three-necked bottle, cool down to 25°C in the cooling device, slowly add 52.95g (0.725 moles) of diethylamine, after the addition of diethylamine, stir at 22°C React for 30 minutes, add 41.4g (0.575 moles) of isobutyraldehyde, heat up to 75°C and react for 7 hours, cool down to 20°C, slowly add 38g (1 mole) of sodium borohydride, after the addition is complete, react for 3.5 hours, slowly Add 80% sulfuric acid until the pH of the feed liquid is 1.0, raise the temperature to 80°C and react for 3.5 hours, cool down to 25°C with the cooling device, adjust the pH of the feed liquid to 7.2 with sodium carbonate solution, extract with ethyl acetate, 280ml each time, combine organic layer, distilled to recover the solvent, and distilled under reduced pressure to obtain 63.5 g of D,L-pantolactone, with a product yield of 97.69% and a purity of 99.07%.
Embodiment 3
[0032] Add 88.8g (0.6 mole) of 50% glyoxylic acid to a 500ml three-necked bottle, cool down to 15°C in the cooling device, slowly add 30.54g (0.3 mole) ethanolamine, after the addition of ethanolamine, stir and react at 30°C for 30 minutes, flow Add 43.2g (0.6 moles) of isobutyraldehyde, heat up to 55°C for 7 hours, cool down to 15°C, slowly add 16.2g (0.3 moles) of potassium borohydride, after the addition is complete, react for 4 hours, slowly add 70% Sulfuric acid until the pH of the feed liquid is 2, heat up to 75°C and react for 4 hours, cool down to 15°C with a cooling device, adjust the pH of the feed liquid to 8 with ammonia water, extract with ethyl acetate, 300ml each time, combine the organic layers, and recover the solvent by distillation. Distilled under reduced pressure to obtain 76.44 g of D,L-pantolactone with a product yield of 98.0% and a purity of 99.23%.
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