Microporous carbon nitride as an effective solid base catalyst for Knoevenagel condensation reactions

Microporous graphitic carbon nitride (CN-Mic) material has been prepared using carbon tetrachloride and ethylene diamine as precursors, and a siliceous microporous MCM-22 as a hard template. A series of Knoevenagel condensation reactions have been performed over the CN-Mic sample, and the influences of reaction conditions on the corresponding catalytic behavior have been investigated. The results showed that the CN-Mic material exhibited high catalytic activity and versatility for the condensation reactions. XPS and FT-IR analysis reveal a high abundance of the N-containing groups located on the surface of CN-Mic, which accounts for the superior catalytic activity of the carbon nitride material as a promising new type of heterogeneous Lewis base catalyst for the condensation reactions. It is also revealed that the activity of CN-Mic is much higher than those obtained over mesoporous g-CN materials. Meanwhile, the catalytic results of CN-Mic compared favorably with those of other g-CN materials for Knoevenagel reactions reported previously. In addition, a mechanism for the CN-Mic catalyzed Knoevenagel condensation was tentatively proposed. (C) 2013 Elsevier B.V. All rights reserved.