| 摘要 |
PROBLEM TO BE SOLVED: To purify the subject compound useful as a synthetic intermediate for a medicine, simply and practically decolorably by bringing a specific piperazinecarboxamide into contact with activated carbon in the presence of a polar organic solvent. SOLUTION: A compound of the formula (R1 and R2 are each H, a 1-10C alkyl, an aryl substitutable with nitro or the like; R3 is a 1-10C alkyl) (e.g. N-tert-butyl-2-piperazinecarboxamide, or the like) is brought into contact with activated carbon having preferably >=10%, based on the whole pore volume, of pore volume of activated carbon having 100-300Åpore diameter in the presence of a polar organic solvent such as methanol or ethyl acetate preferably at a room temperature to the boiling point of the polar organic solvent to obtain the purified objective compound. The amount of the polar organic solvent used is preferably 80-100 wt.% based on the whole amount of the solvent constituting a solution. The amount of the activated carbon used is preferably 5-50 wt.% based on the net weight of the colored compound of the formula.
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