Department of Organic Chemistry, Biochemistry and Catalysis, Faculty of Chemistry, University of Bucharest, 030018 Bucharest, Romania.
Research Center for Catalysts and Catalytic Processes, Faculty of Chemistry, University of Bucharest, 030018 Bucharest, Romania.
Molecules. 2021 Oct 14;26(20):6191. doi: 10.3390/molecules26206191.
Mechanical activation and mechanochemical reactions are the subjects of mechanochemistry, a special branch of chemistry studied intensively since the 19th century. Herein, we comparably describe two synthesis methods used to obtain the following layered double hydroxide doped with cerium, MgAlCe(OH)(CO)·2HO: the mechanochemical route and the co-precipitation method, respectively. The influence of the preparation method on the physico-chemical properties as determined by multiple techniques such as XRD, SEM, EDS, XPS, DRIFT, RAMAN, DR-UV-VIS, basicity, acidity, real/bulk densities, and BET measurements was also analyzed. The obtained samples, abbreviated HTCe-PP (prepared by co-precipitation) and HTCe-MC (prepared by mechanochemical method), and their corresponding mixed oxides, Ce-PP (resulting from HTCe-PP) and Ce-MC (resulting from HTCe-MC), were used as base catalysts in the self-condensation reaction of cyclohexanone and two Claisen-Schmidt condensations, which involve the reaction between an aromatic aldehyde and a ketone, at different molar ratios to synthesize compounds with significant biologic activity from the flavonoid family, namely chalcone (1,3-diphenyl-2-propen-1-one) and flavone (2-phenyl-4H-1benzoxiran-4-one). The mechanochemical route was shown to have indisputable advantages over the co-precipitation method for both the catalytic activity of the solids and the costs.
机械激活和机械化学反应是机械化学的主题，这是一门自 19 世纪以来就被深入研究的化学分支学科。在此，我们分别比较了两种用于合成以下层状双氢氧化物掺杂铈的方法：机械化学法和共沉淀法。通过 XRD、SEM、EDS、XPS、DRIFT、拉曼、DR-UV-VIS、碱度、酸度、真实/体密度和 BET 测量等多种技术对制备方法对物理化学性质的影响进行了分析。所获得的样品，分别缩写为 HTCe-PP（共沉淀法制备）和 HTCe-MC（机械化学法制备），以及它们相应的混合氧化物 Ce-PP（由 HTCe-PP 制备）和 Ce-MC（由 HTCe-MC 制备），被用作环己酮自缩合反应和两种 Claisen-Schmidt 缩合反应的基础催化剂，这两种反应涉及芳香醛和酮之间的反应，摩尔比不同，用于合成具有显著生物活性的黄酮类化合物，即查尔酮（1,3-二苯基-2-丙烯-1-酮）和黄酮（2-苯基-4H-1-苯并恶嗪-4-酮）。与共沉淀法相比，机械化学法在固体的催化活性和成本方面都具有无可争议的优势。
