| 摘要 |
The invention relates to a process for recovering 3-aminomethyl-3,5,5-trimethylcyclohexylamine(isophoronediamine, IPDA) having a cis/trans isomer ratio of at least 73/27 by fractional distillation, which comprises the following steps: a) providing IPDA in a cis/trans isomer ratio of <73/27; b) feeding IPDA into the middle region of a distillation column having internals and distilling the IPDA in this distillation column at a temperature of from 5 to 300° C. and a pressure of from 10 to 2000 mbar; c) optionally further purifying the IPDA obtained by step b) by distilling in at least one further column; where steps b) and c) separate the IPDA used in step a) into at least five fractions ia) to iv): ia) the organic proportion of a fraction of impurities having lower boiling points than tans-IPDA, ib) the aqueous proportion of a fraction of impurities having lower boiling points than trans-IPDA, ii) a fraction of impurities having higher boiling points than cis-IPDA, iii) an IPDA fraction having a cis/trans isomer ratio of >=73/27 and iv) an IPDA fraction having a cis/trans isomer ratio of <=66/34.
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