JPS5742684A - Preparation of epsilon-caprolactone - Google Patents

Abstract

PURPOSE: To obtain ε-caprolactone useful as a raw material of polymer, etc., in high yield, by separating and puritying the reaction mixture obtained by oxidizing cyclohexanone with an organic peracid using a specific distillation method, thereby preventing the polymerization loss during the oxidation and distillation steps.

CONSTITUTION: Cyclohexanone is oxidized with an organic peracid (e.g. peracetic acid, perpropionic acid, etc.), and low-boiling components (acetic acid, ethyl acetate, unreacted cyclohexanone, and peracetic acid) are distilled out from the reaction mixture. After the treatment, the reaction mixture is again distilled with an apparatus furnished with a one-pass thin-film evaporator to obtain the objective compound. For example, the reaction mixture is fed to a column 1 through the pipe 2 to distill off the low-boiling components, and the bottom residue is supplied to the distillation column 4 for removing high-boiling components and furnished with a single-pass thin-film evaporator 5. The by-product (e.g. polycaprolactone and adipic acid) is removed from the bottom of the evaporator 6 and the objective product is obtained from the top 7 of the column. The polymerization loss can be remarkably reduced by the combination of the proper selection of the reaction mixture based on the organic peracid process and the prevention of contact of the high- boiling components with the objective product utilizing the single-pass process.

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