The effect of the sulfation of zirconia catalysts on their structure, acidity/basicity, and catalytic activity/selectivity toward the ketonization of organic acids is investigated by a combined experimental and computational method. Here, we show that, upon sulfation, zirconia catalysts exhibit a significant increase in their Brønsted and Lewis acid strength, whereas their Lewis basicity is significantly reduced. Such changes in the interplay between acid–base sites result in an improvement of the selectivity toward the ketonization process, although the measured conversion rates show a significant drop. We report a detailed DFT investigation of the putative surface species on sulfated zirconia, including the possible formation of dimeric pyrosulfate (S 2 O 7 2– ) species. Our results show that the formation of such a dimeric system is an endothermic process, with energy barriers ranging between 60.0 and 70.0 kcal mol –1 , and which is likely to occur only at high SO 4 2– coverages (4 S/nm 2 ), high temperatures, and dehydrating conditions. Conversely, the formation of monomeric species is expected at lower SO 4 2– coverages, mild temperatures, and in the presence of water, which are the usual conditions experienced during the chemical upgrading of biofuels.

We report a detailed survey of the calculated bulk properties of zirconia using GGA and meta-GGA DFT functionals, Grimme's dispersion, and Hubbard correction in order to identify the best DFT approach for in silico description of zirconia polymorphs.

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Combined experimental and mixed implicit/explicit solvation approaches were employed to gain insights into the origin of switchable regioselectivity of acid‐catalyzed lapachol cyclization and α‐/β‐lapachone isomerization. It was found that solvating species under distinct experimental conditions stabilized α‐ and β‐lapachone differently, thus altering the identity of the thermodynamic product. The energy profile for lapachol cyclization revealed that this process can occur with low free‐energy barriers (lower than 8.0 kcal mol−1). For α/β isomerization in a dilute medium, the computed enthalpic barriers are 15.1 kcal mol−1 (α→β) and 14.2 kcal mol−1 (β→α). These barriers are lowered in concentrated medium to 11.5 and 12.6 kcal mol−1, respectively. Experimental determination of isomers ratio was quantified by HPLC and NMR measurements. These findings provide insights into the chemical behavior of lapachol and lapachone derivatives in more complex environments.

Starting from 2-hydroxy-1,4-naphthoquinone (lawsone), we synthesized eight new 6H-dibenzo[b,h]xanthene derivatives selectively under solvent-free conditions. Spectroscopic investigations confirmed that only the isomer 6H-dibenzo[b,h]xanthene was obtained in all eight cases. Computational studies provide a rationalization for the selective appearance of these isomers having as an intermediate an addition product.