In the present study, the catalytic activity of palladium oxide (PdOx) supported on ceria nanorods (CeO2-NR) for aerobic selective oxidation of benzyl alcohol (BnOH) to benzaldehyde (PhCHO) was evaluated. The CeO2-NR was synthesized hydrothermally and the Pd(NO3)2 was deposited by a wet impregnation method, followed by calcination to acquire PdOx/CeO2-NR. The catalysts were characterized by X-ray diffraction (XRD), temperature programmed reduction (TPR), transmission electron microscopy (TEM), Brunauer–Emmet–Teller (BET) surface area analysis, and X-ray photoelectron spectroscopy (XPS). In addition, the TPR-reduced PdOx/CeO2-NR (PdOx/CeO2-NR-Red) was studied by XRD, BET, and XPS. Characterizations showed the formation of CeO2-NR with (111) exposed plane and relatively high BET surface area. PdOx (x > 1) was detected to be the major oxide species on the PdOx/CeO2-NR. The activities of the catalysts in BnOH oxidation were evaluated using air, as an environmentally friendly oxidant, and various solvents. Effects of temperature, solvent nature and palladium oxidation state were investigated. The PdOx/CeO2-NR showed remarkable activity when protic solvents were utilized. The best result was achieved using PdOx/CeO2-NR and boiling ethanol as solvent, leading to 93% BnOH conversion and 96% selectivity toward PhCHO. A mechanistic hypothesis for BnOH oxidation with PdOx/CeO2-NR in ethanol is presented.

New dihydroxytyrosyl esters 2a, 2c–2j of dicarboxylic acids were synthesized from methyl orthoformate protected hydroxytyrosol 3 and diacyl chlorides. New compounds were characterized (HRMS, FT-IR, 1H- and 13C-NMR), and tested for antioxidant activity both in vitro (ABTS) and on L6 myoblasts and THP1 leukemic monocytes cell culture by DCF assay. According to the ABTS assay, compounds 2a, 2c–2j showed a TEAC value of antioxidant capacity up to twice that of Trolox. Very high or complete ROS protections were obtained in the cell environment where lipophilicity and rigidity of dicarboxylic structure seem to facilitate the antioxidant effect. MTT assay and proliferation test were used for assessment of cell viability. These compounds can be envisaged as a new class of preservatives for food or cosmetic products.

Catalytic aerobic oxidation of benzyl alcohol (BnOH) to benzaldehyde (PhCHO) over supported noble metal catalysts has grabbed the attention of researchers due to the critical role of PhCHO in numerous industrial syntheses. In the present study, a novel catalyst, Pd-P alloy supported on aminopropyl-functionalized mesoporous silica (NH2-SiO2), was prepared through in situ reduction and characterized by BET-BJH analysis, SEM, TEM, XRD, FTIR, TG-DTA, and XPS. Chemical properties and catalytic performance of Pd-P/NH2-SiO2 were compared with those of Pd0 nanoparticles (NPs) deposited on the same support. Over Pd-P/NH2-SiO2, the BnOH conversion to PhCHO was much higher than over Pd0/NH2-SiO2, and significantly influenced by the nature of solvent, reaching 57% in toluene at 111 °C, with 63% selectivity. Using pure oxygen as an oxidant in the same conditions, the BnOH conversion increased up to 78%, with 66% selectivity. The role of phosphorous in improving the activity may consist of the strong interaction with Pd that favours metal dispersion and lowers Pd electron density.

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