| 摘要 |
Acrylonitrile containing methyl vinyl ketone as impurity is purified by treating at elevated temperatures in the acid pH range with a thiocarboxylic acid, an organic thio acid amide or an organic compound containing a mercapto group, and isolating the acrylonitrile from the resulting mixture by fractional distillation. Suitable compounds for use in the process are, for example, n-dodecyl mercaptan, tert-dodecyl mercaptan, octyl mercaptan, mercapto propionic acid, thiopropionic acid, thiophenol and thiourea. Preferably the pH value of the mixture is between 1 and 4 and the desired pH can be obtained by adding, for example, sulphuric acid or toluene sulphonic acid, either before or after the addition of the thio compound to the acrylonitrile. The process may be carried out continuously and if desired stabilisers, such as cyclohexyl pyrocatechol, tertiary-butyl pyrocatechol and phenthiazine may be added to the mixture to prevent polymerisation of the acrylonitrile. |
