Abstract:

A clean and efficient method for N-alkylation of amines catalyzed by Ni-Sn/Al2O3, employing alcohol as the alkylation agent and solvent as well as hydrogen-donor, has been developed. For all the reactions, the temperature is 180℃ ,the pressure is 1.5MPa, and the flow rate is 1.0cm3•min-1.The structure of the catalyst was confirmed by the X-ray diffraction(XRD) and transmission electron microscopy (TEM).The yield of N-alkylation amines was measured by gas chromatography(GC) while its structure confirmed by gas chromatograph-mass spectrometer (GC-MS). The results show that this catalyst has a great conjoint effect for all the reactions in in-situ hydrogenation for N-alkylation, including dehydrogenization of alcohol and hydrogenation of imines being intermediates. As majority of the reactions are concerned, the total yields of all the N-alkylation products are quite good, and some even more than 99% . From the XRD patterns, the Lewis acid sites on the surface of the catalyst should be considered as the active centers in N-alkylation reactions, which eventually became Brфnested ones, as a result that the catalyst becomes inactive. The catalyst has quite a long life-span,which can be more than 480h.

Key words: Liquid-Phase Catalytic N-Alkylation, In-Situ Liquid-Phase Hydrogenation, N-alkylated Amines