Novel MgO-Sn[O.sub.2] solid superbase as a high-efficiency catalyst for one-pot solvent-free synthesis of polyfunctionalized 4H-pyran derivatives

• Published in: Catalysis letters Vol. 142; no. 5; pp. 608 - 614
• Main Authors: Zhang, Shu-Guo, Yin, Shuang-Feng, Wei, Yu-Dan, Luo, Sheng-Lian, Au, Chak-Tong
• Format: Journal Article
• Language: English
• Published: Springer 01.05.2012
• Subjects: Aldehydes; Diffraction; Nitriles; Pyridine; Toy industry; X-rays
• ISSN: 1011-372X; 1572-879X
• DOI: 10.1007/s10562-012-0805-5

We report for the first time the hydrothermal synthesis of MgO-Sn[O.sub.2] solid superbase using P123 as template. The basicity of the materials was determined by two approaches of Hammett indicators method and temperature-programmed desorption using C[O.sub.2] as adsorbate (C[O.sub.2]-TPD). It was found that Mg/Sn molar ratio has an effect on MgO-Sn[O.sub.2] basicity, and superbasicity was observed only at Mg/Sn molar ratio of 1. With variation of Mg/Sn molar ratio, superbase strength was in the 26.5-33.0 range, showing superbasic value up to 0.939 mmol/g. The structure and texture of the as-prepared materials were studied by powder X-ray diffraction (XRD), scanning electron microscopy (SEM), and [N.sub.2] physioadsorption methods. We detected particles of spherical morphology having diameter of ca. 150 nm. [N.sub.2] adsorption-desorption results suggested that the materials are of mesoporous structure, having specific surface area of 115.2 [m.sup.2]/g and average pore diameter of 6 nm. The superbase was found to exhibit excellent catalytic activity towards the one-pot synthesis of polyfunctionalized 4Hpyrans through the condensation of aldehydes, malononitrile, and an active methylene compound. Its excellent catalytic efficiency is related to its superbasicity of the MgO-Sn[O.sub.2]. The results provide a new route for the design and preparation of composite oxide superbases. Furthermore, the solid superbases will facilitate a strategy for high-efficiency synthesis of polyfunctionalized 4H-pyrans.