| 摘要 |
A continuous process for preparing alpha-hydroxycarboxylic esters, in whi ch, as reactants, alpha-hydroxycarboxamide is reacted with an alcohol in the presence of a catalyst to obtain a product mixture which comprises alpha-hy droxycarboxylic ester, ammonia, unconverted alpha-hydroxycarboxamide, and al so alcohol and catalysts; wherein a') reactant streams comprising, as reacta nts, an alpha-hydroxycarboxamide, an alcohol and a catalyst are fed into a p ressure reactor; b') the reactant streams are reacted with one another in th e pressure reactor at a pressure in the range from 1 bar to 100 bar; c') the product mixture which results from step b) and comprises alpha-hydroxycarbo xylic ester, unconverted alpha-hydroxycarboxamide and catalysts, and also am monia and alcohol, is discharged from the pressure reactor; and d') the prod uct mixture is depleted in alcohol and ammonia, ammonia being distilled off at a pressure which is constantly kept greater than 1 bar, without the aid o f additional stripping media. The continuous process can be employed on the industrial scale particularly advantageously.
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