METHOD FOR PRODUCING IPDA WITH A HIGH CIS/TRANS ISOMER RATIO BY DISTILLATION

摘要

The invention relates to a method for obtaining 3-aminomethyl-3,5,5-trimethyl cyclohexylamine (isophorone diamine, IPDA) with a cis/trans isomer ratio of at least 73/27 by fractional distillation. Said method comprises the following steps: a) preparation of IPDA with a cis/trans isomer ratio < 73/27; b) introduction of IPDA into the central zone of a packed distillation column and distillation of the IPDA in said column at a temperature of between 5 and 300 DEG C and a pressure of between 10 and 2000 mbar; c) optional additional purification of the IPDA obtained in step b) by distillation in at least one additional column. According to said method, the IPDA from step a) is separated by means of steps b) and c) into at least five fractions ia) to iv): ia) the organic portion of a fraction of impurities that have a lower boiling point than trans-IPDA, ib) the aqueous portion of a fraction of impurities that have a lower boiling point than trans-IPDA, ii) a fraction of impurities that have a higher boiling point than cis-IPDA, iii) an IPDA fraction with a cis/trans isomer ratio >/=73/27 and iv) an IPDA fraction with a cis/trans isomer ratio