PROCESS FOR PREPARING TRANS-TRANS-4,4'-DIAMINO-DICYLCOHEXY LMETHANE

摘要

A PROCESS FOR THE PREPARATION OF TRANS,TRANS-4,4'-DIAMINO-DICYCLOHEXYLMETHANE The present invention relates to a new and easier process for the preparation of 4,4'-diaminodicyclohexylmethane having a high content of the trans,trans-isomer. This process comprises 1) condensing an isomeric mixture of 4,4'-diamino- dicyclohexylmethane with carbonyl compounds in the presence of a non-polar organic solvent which forms an azeotrope with water, which is heated to remove the reaction water and form the corresponding diimine, 2) isomerizing the solution of diimine by adding at least one base, and at least one polyether and/or c) a crown ether, to the diimine solution and allowing these to act on the diimine for at least 3 hours at room temperature or at an elevated temperature, 3) separating the trans,trans-4,4'-diaminodicyclohexylmethane diimine which crystallizes out of the solution, and 4) hydrolyzing it in a known manner to yield trans,trans-4,4'- diaminodicyclohexylmethane. It is also possible to add seed crystals of the corresponding trans,trans-4,4'-diaminodicyclohexylmethane diimine to the isomerized solution of diimine, or simultaneously while separating the diimine which crystallizes out of the solution. Other variations of the process are also disclosed.