To enable efficient lactam production by recycling the rearrangement catalyst without its deactivation.
After the liquid-phase Beckmann rearrangement of an oxime, for example, using hydrogen chloride as a catalyst, the formed lactam (suitably -caprolactam) is crystallized out and isolated in the form of its hydrochloride, while the reaction mother liquor containing the catalyst is recycled. In order to inhibit the catalyst from being deactivated, the compounds to be used as raw materials are sufficiently dried, preferably the amount of water in the reaction system is ad justed to less than 1 mole per mole of the catalyst and the rearrangement reaction is carried out at ≤150°C. The isolation of the lactam by crystallization is preferably effected in an inert gas atmosphere.
KANAI AYAKO
MORITA SHOJI
