SYNTHESIS OF DIMETHYLETHYLAMINE FROM ETHYLAMINE AND METHANOL OVER COPPER-CATALYSTS

The synthesis of dimethylethylamine (DMEA) from monoethylamine (MEA) a nd methanol was carried out in the presence of a copper chromite type catalyst. A DMEA yield of 70% was obtained under standard experimental conditions, the main by-product being diethylmethylamine. A slight in crease of the basicity without any change in the metallic character of the catalyst can enhance to 85% of the DMEA formation. Indeed with su ch a catalyst modification, the rate of the determining steps was chan ged. By specific experiments involving the reactivity of intermediates it is demonstrated that the rate of the MEA condensation decreased co mpared to that of the MEA methylation. Moreover we show that the mecha nism of the second methylation step which was different from that of t he first methylation could involve an intermediate formation of an ami de (MEFA) or of the surface aminoalkoxide. This step depends also on t he bifunctional character of the modified copper chromite catalyst.