The First Example of Activation of Molecular Oxygen by Nickel in Ni-Al Hydrotalcite: A Novel Protocol for the Selective Oxidation of Alcohols

Abstract

NiO in association with aluminum oxide has been identified by temperature‐programmed reduction as the active species in the Ni–Al hydrotalcite catalyst that oxidizes α‐ketols as well as benzylic and allylic alcohols to their corresponding carbonyl compounds in oxygen in quantitative yields under mild reaction conditions (see scheme).

Oxidation of Cyclohexanol on Phosphotungstic Acid Anion Intercalated Layered Double Hydroxides With Aqueous H2o2 as Oxidant

“…Moreover, it is well known that nickel is usually applied as an active species in the heterogeneous catalysis for the oxidation of alcohol. 28,29 Therefore, the performance could be improved in the oxidation of cyclohexanol with aqueous H 2 O 2 as an oxidant by adding a metal nickel to the binary Mg/Al-LDH. We hereby reported the preparation and characterization of ternary Mg 2 AlNi-POM LDH catalyst using 12-phosphotungstic acid anions ([PW 12 O 40 ] 3-, referred to as "POM") which are intercalated between the LDH layers replacing the nitrate anions via ion-exchange pathway.…”

Environment-Friendly Reduction of Aromatics to Alicyclic Compounds at Room Temperature Using Superactive Calcined Ni-Al Hydrotalcite Catalysts

“…As the nickel content increases, the activity decreases due to presence of more nickel particles in the matrices of the HT which causes lower activity observed in samples of Ni catalysts with ratios of 2.5: 1, and 3: 1 reported by Jonnalgadda et. al [14,[31][32][33][34][35][36][37]. In view of these results the authors investigated the reduction of aromatic substrates which have important applications in petrochemical and chemical industries.…”

“…Ni-Al-CO 3 HT, Ni/Al ratios (2.5 and 3) were prepared similarly by taking appropriate ratios of Ni and Al nitrates". Then the catalysts were calcined in air for 6 hrs at 450 o C in furnace then the obtained catalysts is tested for catalytic reactions [16,30,[35][36]. [14][15][16].…”

“…Cat B prepared using the ammonia method, displays both free NiO and NiO in relationship with aluminium oxide [32][33][34][35][36]. The TPR profile of Ni-Al HT prepared by NaOH/Na 2 CO 3 exhibited a shoulder at lower temperature which grows on increased free NiO content, namely from Ni-Al ratio 2: 1, 2.5: 1 and 3: 1 [16,36]. All these results identify the Ni in association with aluminium oxide as the active species and major foundation to maximize the activation of molecular hydrogen for reduction of aromatics [1].…”

Oxidation of benzoins to benzils in the presence of porphyrin sensitizers by air and sunlight or visible light

“…1,2-Diketones have been synthesized with different reagents, such as oxidation of 1,2-diols [37,38], oxidation of alkynes [39][40][41][42][43][44][45][46][47][48][49], oxidation of alkenes [50], oxidation of a-methylene ketones [51], rearrangement of a,b-epoxyketones [52][53][54], oxidation of vicinal dihaloalkenes [55], oxidation of epoxides [56], oxidation of 1,3-diols [57], and oxidation with molecular oxygen. They have been catalyzed by trichlorooxyvanadium [58], nickel-aluminum hydrotalcite [59], and chiral cobalt complex [60], while palladium-catalyzed oxidation of benzoins to benzils was achieved by using CsOH or K 2 CO 3 as a base [61][62][63]. Porphyrins and metalloporphyrin complexes have been used in numerous biological systems [64].…”