Mesoporous silica polymer nanocomposites encapsulated with polyphosphoric acid for the synthesis of β-amino carbonyl compounds under environmental benign conditions

Abstract

Mesoporous silica–polymer nanocomposites (SBA/PS) synthesized via wet impregnation method were functionalized by mild polyphosphoric acid (PPA) for catalytic applications. The catalysts were characterized and analysed by powder X-ray diffraction (PXRD), solid state nuclear magnetic resonance (³¹P-SSNMR), N₂-adsorption–desorption isotherm, Fourier transform-infrared (FT-IR), scanning electron microscopy (SEM), high resolution transmission electron microscopy (HR-TEM) and thermogravimetric analysis (TGA/DTA). The catalytic studies of a multicomponent Mannich reaction was conducted wherein the hydrophobic nature of these nanocomposites showed an enhancement in the product activity and selectivity of β-amino carbonyl (Mannich base) compounds. The probable reaction mechanism elucidates the role of well-distributed active sites on the hydrophobic surface and the stability of the catalyst for good catalytic activity.