| 摘要 |
Provided is an industrially practicable purification method which affords a polyethylene glycol compound having one amino group with good efficiency and purity and does not discharge any waste such as any adsorbent and any ion-exchange resin. An aqueous solution of the polyethylene glycol is prepared, the aqueous solution having a pH of 1 to 5. This aqueous solution and a mixed organic solvent are mixed together at 10°C or higher and 55°C or lower, causing layer separation into an organic layer and an aqueous layer. The ratio of an organic solvent I is 25 to 65% by mass and the ratio of an organic solvent II is 75 to 35% by mass in the mixed organic solvent. The organic solvent I is selected from an aromatic hydrocarbon-based solvent having a total carbon number of 8 or less and an ester compound solvent containing no hetero atom and having a total carbon number of 5 or less, the organic solvent II is a halogenated hydrocarbon-based solvent, and a mixing ratio Y of the organic solvent I to the organic solvent II (organic solvent I/organic solvent II), temperature T (°C), and molecular weight M of the polyethylene glycol compound satisfy the following relationship. 1.9 × 10 - 6 �¢ M + 0.09 ‰¦ Y - 0.015 �¢ T ‰¦ - 1.4 × 10 - 6 �¢ M + 0.44 |
