Carbon-Carbon Bond Formation and Hydrogen Production in the Ketonization of Aldehydes.
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.
['Orozco|Lina M|LM|', 'Renz|Michael|M|0000-0002-1101-9562', 'Corma|Avelino|A|0000-0002-2232-3527']
D000447:Aldehydes D002244:Carbon D002264:Carboxylic Acids D006538:Heptanoic Acids D006859:Hydrogen D007659:Ketones D008958:Models, Molecular D008968:Molecular Conformation D010084:Oxidation-Reduction D014867:Water D015040:Zirconium
ketones aldehydes carboxylic acids biomass heterogeneous catalysis