Toray Industries, Inc.

Ichiro Kawamoto

Shinzo Imamura

Koji Natsume

Takeshi Sekoguchi

Yoshihiro Shibai

Shinnosuke Sakai

Purified .alpha.-amino-.epsilon.-caprolactam free from not only visible ray-absorbing substances but ultra-violet ray-absorbing substances, such as, tetrahydrophenazine and octahydrophenazine, and volatile basic substances such as, ammonium salts, is obtained by dissolving a crude .alpha.-amino-.epsilon.-caprolactam in a solvent consisting of at least one alkyl ester of saturated aliphatic acid of the formula:

Method for purifying .alpha.-amino-.epsilon.-caprolactam

There is provided an improvement in the process for the amination of bis(2-chloro-1-nitrosocyclohexane) wherein bis(2-chloro-1-nitrosocyclohexane) prepared by reacting cyclohexene with nitrosyl chloride in the presence of liquid sulfur dioxide is treated with ammonia. Sulfur dioxide contained in the nitrosation reaction mixture in the form of a slurry or solution containing bis(2-chloro-1-nitrosocyclohexane) is evaporated in the presence of an inert organic solvent, incorporated into the reaction mixture, and is substantially removed from the reaction mixture. Thereafter, the slurry or solution of bis(2-chloro-1-nitrosocyclohexane) in the inert organic solvent thus prepared is treated with ammonia.

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Nagoya, Japan

Ichiro Kawamoto