K5PW11NiO39‐catalyzed oxidation of benzyl alcohol with hydrogen peroxide

Abstract

In this work, we synthesized a series of metal-substituted potassium heteropolyacid salts and investigated its catalytic activity on oxidation of benzyl alcohol with H 2 O 2 under homogeneous (CH 3 CN) and biphasic (toluene/water) conditions. The Keggin heteropolyacids were converted to lacunar salts (i. e., K 7 PW 11 O 39 ; K 7 PMo 11 O 39 and K 8 SiW 11 O 39 ), which had their vacancies filled with metal cations (i. e., Al 3 + , Fe 3 + , Co 2 + , Cu 2 + , and Ni 2 + ), generating the metal-substituted salts. The K 5 PW 11 NiO 39 proved to be the most efficient catalyst. The synergic effect raised between the PW 11 O 39 7À anion and Ni 2 + cation improved the redox properties and the activity of the catalyst. The K 5 PW 11 NiO 39 catalyst was able to promote the benzyl alcohol oxidation with hydrogen peroxide in biphasic conditions in the absence of phase transfer catalyst. Benzaldehyde and benzoic acid were the main products. The effects of main reaction parameters were assessed. The K 5 PW 11 NiO 39 catalyst was successfully recovered and reused without losing activity.

Oxidation of 1-propanol to propionic acid with hydrogen peroxide catalysed by heteropolyoxometalates

“…The XRD pattern of (ProH) 3 [PW 12 O 40 ] (Fig. 3) shows obvious diffraction peaks at 2θ of 7.8°, 9.7°, 18.3°, 29.1°, 32.5°, and 37.8°, which can reflect the characteristic absorption peaks of Keggin structure [22]. However, the diffraction peaks are not exactly the same as those of H 3 PW 12 O 40 , because the hydrogen proton of H 3 PW 12 O 40 is replaced by the proline cation.…”

“…There have been some reports on the oxidation of primary alcohols using heteropolyoxometalates as catalysts [20][21][22][23]. Nonetheless, these catalysts only promote the oxidation of primary alcohols to the corresponding aldehydes.…”

Tungsten-substituted molybdophosphoric acid impregnated with kaolin: effective catalysts for the synthesis of 3,4-dihydropyrimidin-2(1H)-ones via biginelli reaction

“…[5][6][7] The M 6+ ions can be replaced by many other metal ions, e.g., V 5+ , Co 2+ , Zn 2+ , Ni 2+ etc. [8][9][10][11][12] The Keggin anion is composed of a central tetrahedral XO 4 surrounded by 12 edge and corner sharing metal-oxygen octahedra MO 6 . The octahedra are arranged in four M 3 O 13 groups.…”

Incorporation of Keggin-based H3PW7Mo5O40into bentonite: synthesis, characterization and catalytic applications

“…that can have a prominent impact on the properties of the anion, these are mostly associated with a change in the charge and polarization of the metal-oxo shell. [10][11][12][13][14][15] Furthermore, one or more of the W atoms can be substituted by different heteroatoms that comprise inner transition metals, such as Co, Ni, Mo, V and so on to yield transition-metal substituted POMs. 8,[15][16][17] This compositional modication tunes the reactivity and effects processes such as the acidity and stability of the POMs.…”