| 摘要 |
PROBLEM TO BE SOLVED: To provide a method for producing ketoisophorone fromα-isophorone by the combination of isomerization and oxidation keeping the activity of an oxidizing catalyst. SOLUTION: This method comprises steps of (1) producingβ-isophorone by isomerizingα-isophorone in the presence of an isomerizing catalyst (e.g. a 5-20C aliphatic polybasic carboxylic acid) in isomerizing reactor 1, (2) producing ketoisophorone by oxidizing the obtainedβ-isophorone in an inert solvent with oxygen in the presence of an oxidizing catalyst (e.g. a complex from a transition metal and N,N'-disalicylidenediamine) in oxidizing reactor 2, (3) removing impurities having low boiling points (e.g. unconjugated cyclic ketones) from the reaction mixture in distillation apparatus 3, (4) removing impurities having high boiling points (e.g. the oxidizing catalyst) in distillation apparatus 4, (5) separating ketoisophorone from the solvent in separator 5, and (6) recycling a solvent which contains impurities at 5,000 ppm, weight or less and substantially no ketoisophorone to the oxidation through recycling tube 6.
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