Method for preparing and purifying hydroxyacetic acid by using hydroxyacetonitrile as raw material
A technology of hydroxyacetonitrile and hydroxyacetic acid, applied in the preparation of nitrile, chemical instruments and methods, ammonium sulfate and other directions, can solve the problems of acetone volatile loss, long reaction time, long esterification reaction time, etc., to achieve the reaction conditions Mild and easy to control, easy to operate, easy to recycle
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Embodiment 1
[0031] First add 48 grams of water and 120 grams of 98% concentrated sulfuric acid in a 1000ml four-necked flask equipped with a stirrer, a thermometer, a dropping funnel, and a reflux condenser, turn on the electric heating bowl to heat, and when the temperature rises to 120°C, stir Under the state of starting to slowly add dropwise 228g of hydroxyacetonitrile aqueous solution of 50% (mass ratio). The time for the dripping process of the material liquid and the reflux reaction process is 6 hours, that is, the solid is precipitated in the reaction liquid, the heating is stopped, and the material is cooled. The conversion rate of hydroxyacetonitrile was determined to be 98.73%. Use ammonia water to neutralize the excess residual sulfuric acid, remove a large amount of water under reduced pressure, and then use 657.1 grams of isopropanol solvent for alcohol analysis to desalt three times. The isopropanol solution of glycolic acid obtained at last contains 0.27% (mass ratio) of ...
Embodiment 2
[0033] First add 6.5 grams of water and 120 grams of 98% concentrated sulfuric acid in a 1000ml four-neck flask equipped with a stirrer, thermometer, dropping funnel, and reflux condenser, turn on the electric heating bowl to heat, when the temperature rises to 120 ° C, stir Under the state of starting to slowly add dropwise 228g of hydroxyacetonitrile aqueous solution of 50% (mass ratio). The time for the dripping process of the material liquid and the reflux reaction process is 6 hours, that is, the solid is precipitated in the reaction liquid, the heating is stopped, and the material is cooled. The conversion rate of hydroxyacetonitrile was determined to be 98.70%. Use ammonia water to neutralize the excess residual sulfuric acid, remove a large amount of water under reduced pressure, and then use 585.0 g of absolute ethanol solvent for alcohol analysis, and desalt in three times. Containing 0.21% (mass ratio) of ammonium sulfate in the ethanol solution of glycolic acid ob...
Embodiment 3
[0035] In a 5000L jacketed glass-lined reactor equipped with a glass-lined stirring paddle of a reducer and a thermocouple, first add 378 kg of pure water and 884 kg of 98% concentrated sulfuric acid, and then slowly add 1606 kg of 50% ( mass ratio) of hydroxyacetonitrile aqueous solution. The reaction temperature is controlled between 114-123°C, and the hydrolysis reaction is carried out for 6h-8h. The density of the sampling analysis system is 1.28g / cm 3 (20°C). The reaction mixture was dehydrated by negative pressure in an industrial thin-film evaporator to obtain a paste-like mixture containing glycolic acid, ammonium sulfate and excess residual sulfuric acid. The conversion rate of hydroxyacetonitrile was determined to be 99.28%. Take 472.3 grams of the mixture, neutralize excess residual sulfuric acid with ammonia water, and then distill off the water under reduced pressure, then use 806.1 grams of methanol solvent for alcohol analysis, and desalting is carried out thr...
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