Role of incorporated transition metal on surface properties and catalytic activity of mesoporous vanadium aluminophosphates in the synthesis of tetrahydroquinolin-5-(1H)-ones

Abstract

• Preparation, characterization and study of structural and textural properties of various transition metal incorporated aluminophosphates. • Application of these aluminophosphates as a catalyst in the synthesis of tetrahydroquinolin-5-(1 H )-ones. • Optimization of the reaction conditions in terms of the activity of the catalyst, feed ratio of catalyst. • Synthesis of thirteen tetrahydroquinolin-5-(1 H )-one derivatives at 25°C in ethanol within 30 minutes. • Characterization of the products by FT-IR, 1 H NMR, 13 C NMR and ESI-MS analysis. Aluminophosphate incorporated with transition metals (Co, Cu, Fe, V) were synthesized by co-precipitation method. The synthesized materials were characterized by different techniques (pXRD, FT-IR, N 2 adsorption-desorption, NH 3 -TPD) to understand the structural and textural properties. The incorporation of transition metal into aluminophosphate plays an important role in designing the surface properties like pore size, surface area, and surface acidity. The materials were studied as a catalyst for the synthesis of tetrahydroquinolin-5-(1 H )-ones by a one-pot cyclocondensation reaction of dimedone, substituted benzaldehydes, 4-fluoro/4-nitro phenyl acetonitrile, and ammonium acetate in ethanol at 25 °C. The structures of the compounds were identified and confirmed by FT-IR, 1 H NMR, 13 C NMR and ESI-MS spectral data. The mesoporous nature of vanadium aluminophosphate (VAlP) along with a uniform pore size distribution, high surface acidity, surface area attributes to its high catalytic activity when compared to pure aluminophosphates.