| 摘要 |
Polypyrrolidone is obtained from technical grade pyrrolidone (2) containing for example 0.2-0.4% by weight of impurities, e.g. 0.02% butyrolactone, 0.07% water, some g -pyrrolidylbutyramide and further impurities, by first recrystallizing from an aliphatic alcohol or ketone (see Division C2). The pyrrolidone is polymerized in cyclohexane in the presence of adipoyldipyrrolidone.ALSO:Pyrrolidone-(2) is purified by recrystallization at -70 DEG to +20 DEG C. from an aliphatic alcohol or ketone or mixtures thereof which has a boiling point lower than the boiling point of pyrrolidone-(2). The solvent may be methanol, ethanol, isopropanol, butanol, isobutanol, acetone, methyl ethyl ketone, or diisopropyl ketone and is used in an amount of 1-50%, preferably 5-25%, by weight. The pyrrolidone is dissolved in the solvent at 25-30 DEG C., solid impurities are filtered, and the solution cooled preferably to -30 DEG to +15 DEG C. |
