Process for preparing secondary amines in the liquid phase

A process for preparing a secondary amine of formula I:

• wherein
• R1 and R2 are each independently hydrogen, a linear or branched aliphatic group having 1 to 15 carbon atoms, a cycloaliphatic group having 5 to 10 carbon atoms, a aralkyl group and a phenyl group optionally o-, m- and/or p-substituted by one or more aliphatic groups having 1 to 4 carbon atoms, and
• R3 is a linear or branched aliphatic group having 1 to 15 carbon atoms, a cycloaliphatic group having 5 to 10 carbon atoms, an aralkyl group and a phenyl group optionally o-, m- and/or p-substituted substituted by one or more aliphatic groups having 1 to 4 carbon atoms,
• the process comprising:
• charging an alcohol of formula II, a primary amine of formula III, hydrogen, a hydrogenation catalyst and optionally, a solvent to a hydrogenation reactor;
• aminating the alcohol of formula II
• with the primary amine of formula III and hydrogen in a liquid phase in the presence of the hydrogenation catalyst to obtain a reaction mixture comprising the secondary amine of formula I:
• R3—NH2 III
• wherein
• R1, R2 and R3 are defined above,
• a molar ration of the alcohol of formula II to the primary amine of formula III is from greater than 1:1 to 20:1,
• a temperature of the amination is from 150 to 210° C.,
• a pressure of the amination is from 1 to 300 bar, and
• the hydrogenation catalyst comprises copper on an oxidic support.