Green synthesis of primary nitroalkanes via oxidation of small-molecule aldoximes catalyzed by alkali-modified TS-1
摘要
Modified TS-1 catalysts were prepared by treating TS-1 with different alkalis for the nitration of aldoxime, and the effect of alkali treatment on catalytic performance was investigated. TS-1 was modified using organic amines such as ethylamine (EA), triethylamine (TEA), and tetrapropylammonium hydroxide (TPAOH), as well as inorganic bases such as NaOH, KOH. The catalysts were characterized by XRD, FT-IR, UV-vis, N2 adsorption etc., which showed that the volume of mesopores increased and the skeleton structure remained basically unchanged by the ethylamine-modified TS-1 and the TPAOH-modified TS-1. The highest yield of 1-nitropropane increased 78% when propionaldehyde oxime was catalyzed by the 0.1 mol/L ethylamine treated sample TS-1-EA-0.1. The enhanced catalytic performance of TS-1 after ethylamine treatment may be attributed to the matching between the pore size of modified TS‑1 and the molecular size of propionaldehyde oxime. Subsequently, TS-1-EA-0.1 was used to catalyze acetaldoxime and butyraldehyde oxime. The results revealed that this catalyst was suitable for acetaldehyde oxime as expected, but less effective for the oxidation of butyraldehyde oxime with a larger molecular diameter than propionaldehyde oxime to 1-nitrobutane.
Graphical abstract