Continuous process for refining glyoxal
AssigneeVeba-Chemie Aktiengesellschaft
InventorsRichard Wessendorf, August Sommer, Heinrich Birkelbach
Life of this patent
Estimating the term…
Abstract
An improvement in a process for refining crude glyoxal solutions, especially those obtained by the oxidation of acid aldehyde with nitric acid, wherein the crude glyoxal solution, free of volatile acids, is neutralized, the glyoxal is transformed to the glyoxal semiacetal with an alcohol having 1 to 3 carbon atoms and, after separation of the salts and other impurities, is again hydrolized with water at elevated temperatures. The improvement described involves continuously extracting the glyoxal semiacetal formed with an organic solvent which is immiscible with water, hydrolyzing the extracted glyoxal semiacetal and refining the aqueous glyoxal solution obtained with active charcoal.
Claims7
A process for refining a crude glyoxal solution, especially one obtained by oxidation of acetaldehyde with nitric acid, containing volatile and non-volatile acids which consists essentially of:
- A. distillatively freeing the crude glyoxal solution of volatile acids, and neutralizing the resultant solution by addition of a basic agent at a temperature below 20.degree. C;
- B. contacting the glyoxal with an alcohol having 1 to 3 carbon atoms whereby to form a glyoxal semiacetal of the formula ##STR2## wherein R is C.sub.1 -C.sub.3 alkyl;
- C. Continuously extracting said glyoxal semiacetal with an organic solvent selected from the group consisting of benzene-benzine mixture, methylene chloride, ethylene chloride, carbon tetrachloride, toluene, ethylbenzene and cyclohexane which is immiscible with water;
- D. thereafter hydrolyzing the extracted glyoxal semiacetal by contacting the same with water.
Dependencies are inferred from the claim text.