| 摘要 |
Crude pyridine bases are purified by rectifying them together with 5 to 50% by weight of water based on the weight of the bases to form an azeotropic mixture of the pyridine base and the water and separating the mixture from the impurities contained in the starting pyridine bases. The rectification may be effected at 71-144 DEG C. and after the distillation, four fractions are obtained, i.e. (a) an azeotropic fraction consisting of various impurities and water; (b) an azeotropic fraction consisting of the pure product and water; (c) anhydrous pure product; and (d) the still residue, and the amounts of the above fractions obtained may be regulated by varying the amount of water employed. Any product in fraction (a) may be recovered by conventional means and the whole process may be effected continuously. Impurities which may be removed by the process include benzene, toluene, o-, m- and p-xylenes, methacrylonitrile, isobutyronitrile and dimethylamino acetonitrile, permanganate reducible materials and Ehrlich's reagent positive material. A form of apparatus suitable for carrying out the process is described. Reference has been directed by the Comptroller to Specification 766,387.
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