US 7,256,313 B2Granted

Method for the production of isophorondiamine (ipda, 3-aminomethyl-3,5,5-trimethyl- cyclohexylamine) having a high cis/tran-isomer ratio

AssigneeBASF SE

InventorsFrank Funke, Thomas Hill, Jobst Rüdiger Von Watzdorf, Wolfgang Mattmann, Wolfgang Harder, Erhard Henkes, Gerd Littmann, Manfred Julius

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Abstract

The invention relates to processes for preparing 3-aminomethyl-3,5,5-trimethylcyclo-hexylamine (isophoronediamine, IPDA) having a high cis/trans isomer ratio. IPDA having a cis/trans isomer ratio in the range from 63/37 to 66/34 can be obtained in any desired cis/trans isomer ratio, irrespective of temperature, by reacting IPDA with H2 and NH3 in the presence of a hydrogenation catalyst. IPDA having a cis/trans isomer ratio of at least 73/27 which is an important starting material for the synthesis of polyurethanes and polyamides can be obtained by combining this isomerization process with distillative processes.

Claims20

Dependent claims

A process for preparing substantially pure 3-aminomethyl-3,5,5-trimethylcyclohexylamine (isophoronediamine, IPDA) having a cis/trans isomer ratio of at least 73/27, comprising the following steps:

a) providing crude IPDA having a cis/trans isomer ratio of <73/27;
b) purifying and separating, by distillation or by crystallization, the crude IPDA into a fraction having a cis/trans isomer ratio of at least 73/27 and a fraction having a cis/trans isomer ratio of less than 63/37;
c) isomerizing the fraction of substantially pure IPDA having a cis/trans isomer ratio of less than 63/37 obtained in step b) to IPDA having a cis/trans isomer ratio in the range from 63/37 to 66/34 in the presence of H2, NH3 and a hydrogenation catalyst and recycling it into step a) of the process.

Dependencies are inferred from the claim text.