Friedlander condensation reaction catalysed by hafnium-based metal-organic framework

Abstract

Heterogeneous catalysis using metal-organic frameworks (MOFs) is one of the attractive fields in recent years because MOFs offer tuneable properties and a broad range of active sites. In this context, synthesis and characterization of UiO-66(Hf)-(NHCOMe)2 (1) and its activated form (1′) are reported. The catalytic behavior of 1′ was investigated in the Friedlander condensation between 2-aminoacetophenone with acetylacetone under mild reaction conditions. The reaction between 2-aminoacetophenone and acetylacetone in the presence of 1′ afforded a quantitative yield of the desired product. On the other hand, the stability of 1′ was also examined by reusing the solid catalyst and characterizing the recovered solid catalyst by powder XRD, FESEM, 1H NMR, 13C NMR, ATR-IR and BET methods. These combined data indicate that the solid catalyst undergoes a structural change by losing its catalytic activity in the first reuse and becomes deactivated. Although no significant changes were observed between the fresh and the recovered solid by powder XRD, FESEM, 1H NMR, 13C NMR, ATR-IR, the significant decrease in BET surface area of the recovered solid suggests the possible pore blocking by the products.