A facile designed highly moderate craspedia flowerlike sulphated Bi2O3-fly ash catalyst: Green synthetic strategy for (6H-pyrido[3,2-b]carbazol-4-yl)aniline derivatives in water

The air pollutant fly ash was facile designed as a green catalyst and practical to organic synthesis. We have designed sulfated Bi2O3-fly ash catalyst (12wt%) and it was characterized by Fourier transform infrared (FT-IR), confocal Raman, Powder X-ray diffraction (XRD), Field emission electron microscopy (FE-SEM), elemental color mapping, energy-dispersive X-ray spectroscopy (EDS), Transmission electron microscopy (TEM) and Brunauer–Emmett–Teller (BET) techniques. The sulfated Bi2O3-fly ash was found an excellent catalytic application for the synthesis of (6H-pyrido[3,2-b]carbazol-4-yl)aniline derivatives in water has been described. The synthesized (6H-pyrido[3,2-b]carbazol-4-yl)aniline derivatives were confirmed by spectral techniques Fourier transform infrared (FT-IR), Nuclear magnetic resonance (NMR) and Liquid chromatography–mass spectrometry (LC–MS). The significant catalytic role of Bi–N interaction was readily form adduct, moreover Bi–O bond was favorable for hydrogen abstraction, dehydration and aromatization. Due to the strong potential, the precise reaction time and high yield have been achieved, which is realized from hot filtration test. The sulfated Bi2O3-fly ash catalyst could be reused for five successive run, the resulting in no appreciable change in the catalytic activity. The crystal phase and surface morphology of fifth run catalyst were examined by powder XRD, FE-SEM, EDS and TEM techniques, and the results revealed no changes in catalyst nature. The sulfated Bi2O3-fly ash catalyst has high efficiency, reusability, good catalytic activity, environmentally harmless and notable potential in industrial applications.