| 摘要 |
PROBLEM TO BE SOLVED: To economically, selectively and efficiently reduce the concentration of amines existing in an N-substituted lactam as an impurity by treating a polluted N-substituted lactam with an acidic macroporous cation exchanger. SOLUTION: (A) An N-substituted lactam polluted with amines is treated with (B) an acidic macroporous cation exchanger. A strong acidic macroporous cation exchanger is used in the treatment and the component B has a styrene- divinylbenzene copolymer base material having 10-150 nm pore diameter. The usable capability of the component B is at least 0.5 mol of amines per 1 L of the cation exchanger and the component A is useful for purification of a compound expressed by the formula [R is a (substituted) saturated aliphatic group or the like; (n) is 1-4], especially for N-methyl-2-pyrrolidone, and the treatment is preferably performed at 5-130 deg.C.
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