Amines functionalized C60 as solid base catalysts for Knoevenagel condensation with high activity and stability

Abstract

Four kinds of amines functionalized C₆₀ were prepared through an amination reaction of C₆₀ with organic amines. Their surface structures and basic properties were studied by Fourier transform infrared spectrometry (FTIR), X-ray photoelectron spectroscopy (XPS) and temperature-programmed desorption (TPD) with CO₂ as the probe molecule. When used as solid base catalysts, N-aminoethylpiperazine functionalized C₆₀ (C₆₀-AEP) showed the best catalytic activity in the Knoevenagel condensation reaction due to the highest basic strength. In addition, the C₆₀-AEP catalyst also showed impressive catalytic stability. All these features endowed C₆₀-AEP with characteristics of both homogeneous and heterogeneous catalysts. More interestingly, chiral L-lysine functionalized C₆₀ (C₆₀-L-L) can be used for asymmetric intermolecular aldol reactions.