CuO-Fe(III)-Zeolite-Y as efficient catalyst for oxidative alcohol-amine coupling reactions

Nb2O5/Ce1–xNbxO2−δ Nanorod Catalyst for Selective Oxidative Coupling of Aromatic Alcohols and Amines

“…The highly dispersed Nb 2 O 5 in the NbCeNR4 nanocatalyst (Figure ) is the reason for its higher Lewis acidic strength (i.e., Nb 5+ species). ,− As shown in Figure , the activation of molecular oxygen by oxygen vacancies in the ceria lattice is crucial for the oxidative dehydrogenation of benzyl alcohol to benzaldehyde. The XPS studies confirmed that the NbCeNR4 nanocatalyst contains more Ce 3+ ions associated with the oxygen vacancies (Figure c,d), which react with molecular oxygen to generate activated oxygen, a well-known fact in the literature. − Thus, the combination of Lewis acid sites and oxygen vacancies is a key factor for the higher activity of the NbCeNR4 nanocatalyst in the C–N coupling of benzyl alcohol with aniline and o-phenylenediamine.…”

“…In the oxidative C–N coupling reactions performed in this work, the simultaneous activation of both benzyl alcohol and molecular oxygen is essential to obtain the benzaldehyde intermediate, which will be eventually attacked by NH 2 of the amine (Schemes S1 and S2, Supporting Information). For this, the catalyst must contain adequate Lewis acid sites, which play a dual role: (a) interacting with the lone pair of −OH group of benzyl alcohol to induce oxidative dehydrogenation step in the presence of an oxidant to obtain the benzaldehyde intermediate and (b) increasing the electrophilic nature of the carbonyl carbon of benzaldehyde to stimulate its condensation with –NH 2 group of aniline or o-phenylenediamine. − The pyridine-adsorbed FT-IR studies showed that the NbCeNR4 nanocatalyst contains more Lewis acid sites than the pure CeO 2 nanorods (CeNR4) and NbCeNR5 material (Figure ). The highly dispersed Nb 2 O 5 in the NbCeNR4 nanocatalyst (Figure ) is the reason for its higher Lewis acidic strength (i.e., Nb 5+ species). ,− As shown in Figure , the activation of molecular oxygen by oxygen vacancies in the ceria lattice is crucial for the oxidative dehydrogenation of benzyl alcohol to benzaldehyde.…”

“…The geometry of these crystal facets facilitates enhanced accessibility of cerium and oxygen atoms on the surface of ceria; thus, the amount of Ce 3+/4+ species and oxygen vacancies can be optimized effectively, depending on the application of CeO 2 in heterogeneous catalysis. The rod-shaped CeO 2 is catalytically active for numerous applications, such as environmental pollution control, − biomass valorization, − CO 2 conversion, − and organic chemical transformations. ,− The oxidative coupling of alcohols and amines to produce nitrogenous chemicals is one of the important applications of shape-controlled ceria nanomaterials including nanorods in organic synthesis. − Nitrogenous chemicals, such as imines and benzimidazoles, are essential building blocks for medicinal chemistry and the pharma industry. − Using cost-effective chemicals, such as benzyl alcohol and aniline, for the synthesis of nitrogenous compounds is considered a promising strategy from an economic point of view.…”