The nano-sized particles enhance the exposed surface area of the active part of the catalyst, thereby increasing the contact between precursors and catalyst considerably. In this study, nano-SiO2/1,5-diazabicyclo[4.3.0]non-5-en was synthesized, characterized and used as a heterogeneous nanocatalyst for the synthesis of tetrahydrobenzo[b]pyran derivatives. Fourier Transform Infrared Spectroscopy, Field Emission Scanning Electron Microscopy, Brunauer–Emmett–Teller plot, Energy Dispersive X-ray Spectroscopy and Thermo Gravimetric Analysis were used to discern nano-SiO2/1,5-diazabicyclo[4.3.0]non-5-en. Tetrahydrobenzo[b]pyrans were synthesized by using nano-SiO2/1,5-diazabicyclo[4.3.0]non-5-en via one-pot three-component condensation of malononitrile, aldehydes and dimedone in H2O/EtOH at 60 °C. The results indicate that tetrahydrobenzo[b]pyrans were synthesized in good to high yields and short reaction times. The fundamental privileges of this method are short reaction time, plain procedure, recyclability of catalyst and high yields of products.

中文翻译：

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Nano-SiO2/DBN：一种有效且可重复使用的催化剂，用于一锅合成四氢苯并[b]吡喃衍生物


纳米尺寸的颗粒增强了催化剂活性部分的暴露表面积，从而显着增加了前体和催化剂之间的接触。在本研究中，合成了纳米SiO2/1,5-二氮杂双环[4.3.0]non-5-en，并对其进行了表征，并将其用作合成四氢苯并[b]吡喃衍生物的多相纳米催化剂。采用傅里叶变换红外光谱、场发射扫描电子显微镜、Brunauer-Emmett-Teller 图、能量色散 X 射线光谱和热重分析来辨别纳米 SiO2/1,5-二氮杂双环[4.3.0]non-5- en.以纳米SiO2/1,5-二氮杂双环[4.3.0]non-5-en为原料，丙二腈、醛类和双甲酮在60 ℃下于H2O/EtOH中一锅三组分缩合反应合成四氢苯并[b]吡喃。 。结果表明，四氢苯并[b]吡喃的合成收率良好至高且反应时间短。该方法的基本特点是反应时间短、流程简单、催化剂可回收、产物收率高。