Synthesis of magnetic Fe3O4@g-C3N4-SO3H composite and its application for the synthesis of α-amido alkyl-β-naphthols

Magnetically separable g-C3N4 composite functionalized with SO3H groups (Fe3O4@g-C3N4-SO3H) was synthesized by polymerizing melamine on commercial nano Fe3O4 to prepare magnetic g-C3N4 followed by sulfonation. Catalytic activity of this composite was checked for the synthesis of fifteen alpha-amido alkyl-beta-naphthols under solvent free conditions. The prepared catalyst exhibited excellent activity with an appreciable yield (60-93 %) in a short duration of time (15-240 min). The catalyst was active towards wide range of aromatic, heterocyclic as well as aliphatic aldehydes. The catalyst was recovered using an external magnetic field and reused for four consecutive cycles without any appreciable loss in its catalytic activity. Physical structure of the composite was studied by SEM and TEM analysis and the crystal structure by powder XRD. Surface area and porosity were determined using nitrogen adsorption-desorption via BET analysis. Elemental composition was determined by SEM-EDS and CHNS analysis. Acidity was measured using an ammonia temperature programme desorption technique and pH determination by back titration. Functional groups were studied by FTIR and thermal stability by TGA-DTA.