Origin of selectivity in surface functionalized vinylpyridine mesoporous silica nanocomposites (VP/SBA) for Henry reaction

To understand the origin of product selectivity, vinyl pyridine (VP) functionalized mesoprous silica nanocomposites were synthesized via two different methods (co-condensation and post grafted polymerization method) for possible influence of synergism in Henry reaction. The physicochemical characterization method (PXRD, N₂-adsorption–desorption, FT-IR, TGA and SEM–EDX, etc.) of the functionalized nanocomposites revealed the retention of mesoporous structural order. The synthesized nanocompostes were exploited for catalytic activity studies for the condensation of 4-methylbenzaldehyde with nitroethane in the liquid phase. The catalytic activity studies showed a significant influence of synthesis methodology for the competitive selectivity of the desired products (Scheme 1). All the standard reaction parameters were optimized to yield better conversion and selective product. Finally, the mechanism of the product formation is proposed and explained.