| 摘要 |
FIELD: chemistry. ^ SUBSTANCE: invention relates to an improved method of producing n-phenylenediamine, involving synthesis of terephthalic acid diamine, Hofmann rearrangement through successive treatment of diamine, first with aqueous sodium or potassium hydroxide solution and then with aqueous sodium or calcium hypochlorite solution, and extraction of n-phenylenediamine. The method involves extraction of n-phenylenediamine from a water-salt solution obtained after Hofmann rearrangement, which is carried out through predistillation of water via azeotropic distillation under a nitrogen blanket with an organic solvent with complete displacement of water and transfer of n-phenylenediamine from an aqueous phase to an organic phase, followed by decantation of the organic phase, crystallisation of n-phenylenediamine from the organic solvent, cooling to temperature not higher than 10C, with separation of the crystallised n-phenylenediamine and separation of the formed salt residue which is subjected to extraction at least thrice with an additional amount of the same solvent used for azeotropic water distillation. Extraction is carried out at temperature 56-140C, followed by extraction of n-phenylenediamine via crystallisation from an extract filtered from the salt residue. ^ EFFECT: method reduces loss of the end product during extraction thereof from the reaction mass and increases quality and output of the end product. ^ 2 cl, 5 ex |
