A simple continuous reaction for the synthesis of quinoline compounds

In this paper, 2-methylquinoline compounds were synthesized continuously from nitroarenes and the ethanol/water system by a simple hydrogen transfer reaction in the presence of the Ru–Fe/γ-Al2O3 catalyst. This new simple synthesis reaction was heterogeneous and continuous. At the same time, green solvents were used, and strong acids, oxidants, and other environmentally harmful substances were not added, which conformed to the principles of green chemistry. Through the impregnation method, the nanocatalysts with a smaller particle size and uniform dispersion were obtained on the γ-Al2O3 particles (1–2 mm) and had good activity. The effects of the alcohol water volume ratio, pressure, flow rate and Ru–Fe mass ratios on the yields of 2-methylquinoline compounds in the reaction were investigated. The reaction can proceed smoothly for nitroarenes with different substituents, and a moderate to good yield (46%–88%) was obtained.