Patent ID: 6936724

Claim:
A process for producing ε-caprolactone by the oxidation of cyclohexanone, comprising the steps of: feeding a crude reaction mixture to a first distillation column having a column bottom temperature from about 100° C. to about 200° C. and a column top pressure of about 100 mmHg or less; distilling off a first distillate from the top of the first distillation column, the first distillate containing low boiling components including unreacted cyclohexanone; recovering a first side-cut fraction from an intermediate tray of the first distillation column, the first side-cut fraction containing unreacted cyclohexanone in a higher concentration than in the first distillate; recovering a first bottom liquid from the bottom of the first distillation column, the first bottom liquid containing high boiling components including ε-caprolactone; 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 ε-caprolactone from the third distillation column.