Synthesis, characterization and application of magnetic biochar sulfonic acid as a highly efficient recyclable catalyst for preparation of spiro-pyrazolo[3,4-b]pyridines
microscope, transmission electron microscope and vibrating sample magnetometer techniques. The prepared catalyst exhibited excellent catalytic activity for synthesis of spiro-pyrazolo[3,4-b]pyridine derivatives via one-potthree-componentreaction of 1H-pyrazol-5-amine, isatin and 3-oxo-3-phenylpropanenitrile. The catalyst could be readily recovered and reused several times without an obvious decay of
采用傅里叶红外光谱(FT-IR)、粉末X射线衍射技术、扫描电镜、透射电镜和振动样品磁强计技术制备磁性生物炭磺酸并对其进行表征。制备的催化剂对1 H-吡唑-5-胺、靛红和3-氧代-3-苯基丙腈的一锅三组分反应合成螺吡唑并[3,4- b ]吡啶衍生物表现出优异的催化活性。该催化剂可以很容易地回收和多次重复使用,而催化性能没有明显下降。