Effect of the C-alpha substitution on the ketonic decarboxylation of carboxylic acids over m-ZrO2: the role of entropy

[EN] The kinetics of the ketonic decarboxylation of linear and branched carboxylic acids over m-ZrO2 as a catalyst has been investigated. The same apparent activation energy is experimentally determined for the ketonic decarboxylation of both linear pentanoic and branched 2-methyl butanoic acids, while the change in entropy for the rate-determining step differs by nearly 50 kJ mol(-1). These results show that the difference in reactivity between linear and branched acids is due to entropic effects, and is related to the probability of finding the reactant molecules adsorbed and activated in a suitable way on the catalyst surface.The authors thank MINECO (Consolider Ingenio 2010-MULTICAT, CSD2009-00050 and Severo Ochoa program, SEV-2012-0267), Generalitat Valenciana (PROMETEOII/2013/011 Project), and the Spanish National Research Council (CSIC, Es 2010RU0108) for financial support. Red Espanola de Supercomputacion (RES) and Centre de Calcul de la Universitat de Valencia are gratefully acknowledged for computational facilities and technical assistance. A. P., F. G. and B. O.-T. thank MINECO (Juan de la Cierva and FPU Programme) and CSIC (JAE Programme) for their fellowships, respectively. M. R. is grateful to the Generalitat Valenciana for a BEST 2015 fellowship.Oliver-Tomás, B.; Gonell-Gómez, F.; Pulido, A.; Renz, M.; Boronat Zaragoza, M. (2016). Effect of the C-alpha substitution on the ketonic decarboxylation of carboxylic acids over m-ZrO2: the role of entropy. Catalysis Science and Technology. 6(14):5561-5566. doi:10.1039/c6cy00395hS5561556661