Immobilization of Proline onto Al-SBA-15 for C–C Bond-Forming Reactions
2014
Guan, Jingqi | Liu, Bo | Yang, Xiaoyuan | Hu, Jing | Wang, Chunhua | Kan, Qiubin
Bifunctionalized materials with different matches of acid and base have been prepared through a post-grafted approach. The synthesized materials were characterized by X-ray diffraction (XRD), nitrogen adsorption–desorption isotherms, XRF analysis, elemental analysis, transmission electron microscopy, IR spectra of pyridine adsorption, thermogravimetry, and CO₂-TPD. The characterization results indicated that the organic amines have been successfully immobilized onto the surface of SBA-15 and Al-SBA-15, and the structure of the supports were kept intact. Moreover, the strength of the acidity for Al-SBA-15 is stronger than that for SBA-15, while the strength of the basicity for tert-butyl 2-(3-(triethoxysilyl)propylcarbamoyl)pyrrolidine-functionalized SBA-15 or Al-SBA-15 is stronger than that for 3-aminopropyltriethoxysilane-functionalized SBA-15 or Al-SBA-15. The synthesized bifunctional acid–base materials were tested in a Knoevenagel reaction, tandem deacetalization–Knoevenagel reaction, one-pot deacetalization–Henry reaction, aldol reaction, and nitroaldol reaction. The catalytic results showed that different acid–base matches favored different reactions.
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