| 摘要 |
PROBLEM TO BE SOLVED: To provide a method for purifying the crude acetic anhydride, giving a purified acetic anhydride which can improve quality of polyoxytetramethylene glycol(PTMG), etc. SOLUTION: This method for purifying the crude acetic anhydride comprises distilling the crude acetic anhydride, then charging a packed tower 2 with the distilled crude acetic anhydride together with ozone-containing air generated by an ozone generator 1, and further subjecting the charged mixture to ozonization. Thus the purified acetic anhydride of which the diketene content is not higher than the detection limit can be obtained, because the acetic anhydride is subjected to ozonization after the distillation. The PTMG which is almost colorless, transparent, and excellent in color can be produced by using the purified acetic anhydride.
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