Orozco Lina M, Renz Michael, Corma Avelino
Instituto de Tecnología Química, Universitat Politècnica de Valencia-Consejo Superior de Investigaciones Científicas (UPV-CSIC), Av. de los Naranjos s/n, E-46022, Valencia, Spain.
ChemSusChem. 2016 Sep 8;9(17):2430-42. doi: 10.1002/cssc.201600654. Epub 2016 Aug 19.
Aldehydes possess relatively high chemical energy, which is the driving force for disproportionation reactions such as Cannizzaro and Tishchenko reactions. Generally, this energy is wasted if aldehydes are transformed into carboxylic acids with a sacrificial oxidant. Here, we describe a cascade reaction in which the surplus energy of the transformation is liberated as molecular hydrogen for the oxidation of heptanal to heptanoic acid by water, and the carboxylic acid is transformed into potentially industrially relevant symmetrical ketones by ketonic decarboxylation. The cascade reaction is catalyzed by monoclinic zirconium oxide (m-ZrO2 ). The reaction mechanism has been studied through cross-coupling experiments between different aldehydes and acids, and the final symmetrical ketones are formed by a reaction pathway that involves the previously formed carboxylic acids. Isotopic studies indicate that the carboxylic acid can be formed by a hydride shift from the adsorbed aldehyde on the metal oxide surface in the absence of noble metals.
醛类具有相对较高的化学能，这是坎尼扎罗反应和季先科反应等歧化反应的驱动力。一般来说，如果醛类用牺牲性氧化剂转化为羧酸，这种能量就会被浪费。在此，我们描述了一种级联反应，其中转化过程中的多余能量以分子氢的形式释放出来，用于水将庚醛氧化为庚酸，并且羧酸通过酮脱羧反应转化为潜在具有工业相关性的对称酮。该级联反应由单斜氧化锆（m-ZrO₂）催化。通过不同醛类和酸之间的交叉偶联实验研究了反应机理，最终的对称酮是通过涉及先前形成的羧酸的反应途径形成的。同位素研究表明，在没有贵金属的情况下，羧酸可以通过金属氧化物表面吸附的醛的氢化物转移形成。
