Preparation of secondary amines from nitriles

摘要

Secondary amines of the formula (II)(X-CH2-)2NH (II)where X is a C1-20-alkyl, C2-20-alkenyl or C3-8-cycloalkyl group which may be unsubstituted or substituted by C1-20-alkyl, C3-8-cycloalkyl, C4-20-alkylcycloalkyl, C4-20-cycloalkylalkyl, C2-20-alkoxyalkyl, C6-14-aryl, C7-20-alkylaryl, C7-20-aralkyl, C1-20-alkoxy, hydroxy, C1-20-hydroxyalkyl, amino, C1-20-alkylamino, C2-20-dialkylamino, C2-12-alkenylamino, C3-8-cycloalkylamino, arylamino, diarylamino, aryl-C1-8-alkylamino, halogen, mercapto, C2-20-alkenyloxy, C3-8-cycloalkoxy, aryloxy and/or C2-8-alkoxycarbonyl, are prepared by reacting nitriles of the formula (III)X-CN (III)with hydrogen at from 20 to 250° C. and pressures of from 60 to 350 bar in the presence of an Rh-containing catalyst comprising from 0.1 to 5% by weight, based on the total weight of the catalyst, of Rh on a support to give mixtures of primary amines of the formula (I)X-CH2-NH2 (I)and secondary amines of the formula (II)(X-CH2-)2NH (II)and returning at least part of the primary amines separated from the mixtures obtained to the reaction.