In this study, flavanone was synthesized via a two-step process, Claisen–Schmidt condensation between 2’-hydroxyactophenone and benzaldehyde followed by isomerization, in subcritical water with ZrO based catalysts. Kinetic analysis was conducted to quantitatively show the catalytic activity of different modified ZrO. The activity of ZrO was improved upon incorporating with active metal species. Compared with La-ZrO and Mg-ZrO, Ca-ZrO showed the highest activity attributed to strong basicity, but substantial formation of side product and loss of product were observed. La-ZrO showed weaker activity than Mg-ZrO, though La-ZrO had higher basicity. One explanation was the dissociation of water to provide OH on the catalyst surface was more challenging since containing significantly more active sites with strong water affinity. Moreover, such active sites contributed less to reaction due to dense water surrounding the catalyst surface. The reaction catalyzed by Mg-ZrO reached flavanone selectivity of 72.2 % in 3 hours at 150 °C.

中文翻译：

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La-ZrO2、Mg-ZrO2 和 Ca-ZrO2 固体碱催化剂在亚临界水中合成黄烷酮的研究


在这项研究中，黄烷酮是通过两步法合成的，即 2'-羟基苯乙酮和苯甲醛之间进行克莱森-施密特缩合，然后在亚临界水中用 ZrO 基催化剂进行异构化。进行动力学分析以定量显示不同改性ZrO的催化活性。与活性金属物质结合后，ZrO 的活性得到改善。与 La-ZrO 和 Mg-ZrO 相比，Ca-ZrO 由于强碱性而表现出最高的活性，但观察到副产物的大量形成和产物的损失。尽管 La-ZrO 具有较高的碱性，但 La-ZrO 的活性比 Mg-ZrO 弱。一种解释是，由于含有更多具有强水亲和力的活性位点，因此在催化剂表面解离水以提供 OH 更具挑战性。此外，由于催化剂表面周围有密集的水，这样的活性位点对反应的贡献较小。 Mg-ZrO催化反应在150℃下3小时内黄烷酮选择性达到72.2%。