| 摘要 |
PURPOSE:To remove an alkali cyanide in the form of hydrogen cyanide gas from N-phenylglycine alkali metal salt useful as an intermediate of indigo dye and obtained by the reaction of aniline, formaldehyde and hydrocyanic acid, by blowing carbon dioxide gas into the reaction product. CONSTITUTION:N-Phenylglycine nitrile obtained by the reaction of aniline with formaldehyde and hydrocyanic acid in the presence of water is hydrolyzed in the presence of an alkali hydroxide to obtain an aqueous solution containing N-phenylglycine alkali metal salt. The alkali cyanide dissolved in the aqueous solution can be removed in the form of hydrogen cyanide gas by blowing carbon dioxide gas into the solution. EFFECT:The content of the alkali cyanide can be reduced to as low as about 5ppm, and the problems of dye preparation or waste water treatment can be solved. There is no lowering of the purity in contrast with the case using an oxidizng agent such as hydrogen peroxide.
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