A process produces -caprolactone by the oxidation of cyclohexanone by
feeding
a crude reaction mixture to a first distillation column; distilling off a first
distillate containing low boiling components including unreacted cyclohexanone
from the top of the first distillation column; recovering a first side-cut fraction
containing unreacted cyclohexanone in a higher concentration than in the first
distillate from an intermediate tray; recovering a first bottom liquid containing
high boiling components including -caprolactone from the bottom; introducing
the first side-cut fraction to a second distillation column; recovering a second
bottom liquid containing unreacted cyclohexanone from the bottom of the second
distillation column; recycling the second bottom liquid into the raw material cyclohexanone;
introducing the first bottom liquid to a third distillation column to thereby yield
a third distillate containing -caprolactone from the third distillation column.