To provide a method for producing -caprolactone, by which the -caprolactone having excellent thermal coloration resistance is obtained, on the production of the -caprolactone by the cooxidation of cyclohexanone and an aldehyde, and to provide low colored polycaprolactone.
This method for producing -caprolactone comprises cooxidizing cyclohexanone and an aldehyde and then distilling the obtained reaction mixture to separate impurities from the -caprolactone. Therein, the -caprolactone separated with a rectifier is brought into contact with an oxygen-containing gas in the presence of cobalt and then distilled to remove a high boiling point fraction. The obtained -caprolactone has an acid value of ≤0.15 mgKOH/g. A high boiling point fraction and a low boiling point fraction are preferably removed by the distillation to give the -caprolactone having an acid value of ≤0.15 mgKOH/g. The cobalt is preferably used in an amount of 0.001 to 10 ppm (weight ratio) based on the -caprolactone.
OGOSHI ATSUSHI
OGAWA HIROSHI
