A facilely designed, highly efficient green synthetic strategy of a peony flower-like SO42−–SnO2-fly ash nano-catalyst for the three component synthesis of a serendipitous product with dimedone in water

Abstract

For the first time we have successfully found a serendipitous product 2-((2-((9-ethyl-9H-carbazol-3-yl)amino)-4,4-dimethyl-6-oxocyclohex-1-en-1-yl)(phenyl)methyl)-5,5-dimethylcyclohexane-1,3-dione and its derivatives by utilizing a SO₄²⁻–SnO₂-fly ash nano-catalyst in water. We have designed a SO₄²⁻–SnO₂-fly ash nano-catalyst which is easily separable, has good catalytic activity, good reusability and notable industrial applications. The catalytic role of Sn–O involves its high affinity with the carbonyl group of dimedone. The major component of fly ash (SiO₂) may enhance the catalytic activity of oxidation processes. With these properties, the conversion of product could be rapid and high yielding. The facilely designed, SO₄²⁻–SnO₂-fly ash nano-catalyst was characterized by Fourier transform infrared spectroscopy (FT-IR), confocal Raman spectroscopy, powder X-ray diffraction (PXRD), field emission electron microscopy (FE-SEM), energy dispersive X-ray spectroscopy (EDS and elemental color mapping), high resolution transmission electron microscopy (HR-TEM) and UV-Visible diffuse reflectance spectroscopy (UV-Vis DRS) techniques. The nano-cube and peony flower like morphologies were found in the FE-SEM and HR-TEM images. The flower like SO₄²⁻–SnO₂-fly ash catalyst’s highly stable nature is favorable for organic reactions. The crystalline nature, surface morphology, chemical composition and morphology of the reused SO₄²⁻–SnO₂-fly ash nano-catalyst were proved by PXRD, FE-SEM, EDAX and HR-TEM analyses respectively. The facilely designed SO₄²⁻–SnO₂-fly ash nano-catalyst is versatile from both environmental and economical points of view. The synthesized serendipitous product derivatives and byproducts were characterized by FT-IR, nuclear magnetic resonance (NMR) and high resolution-mass spectrometry (HR-MS).