Role of vanadium and pyridine in heteropolycompounds for selective oxidation of alcohols with hydrogen peroxide

Abstract

and a hybrid pyridine-modified heteropolyacid with Keggin structure for selective oxidation of alcohols to ketones or aldehydes using aqueous hydrogen peroxide and acetonitrile as solvent. Performance of these different catalysts in 1-phenylethanol oxidation was studied. Influence of reaction temperature, amount of catalyst and hydrogen peroxide and reaction time on the yield of acetophenone was investigated to obtain optimal reaction conditions. Oxidation ability of the catalyst depended on the number of vanadium atoms present in the Keggin ion and to a lesser extent on pyridine substitution in the Keggin secondary structure. In order to explore the applicability of the method for selective oxidation of alcohols to ketones or aldehydes, various alcohols were investigated according to the general procedure using hybrid pyridine-modified heteropolyacid.

Easy Scale‐Up Synthesis of Mo8O26(C5H6N)4.H2O Hybrid with a Rectangular Prism Morphology and Its Application as an Efficient and Highly Recyclable Bi‐functional Catalyst for Knoevenagel Condensations

“…Under optimized reaction conditions, no oxidation took place in the presence of pyridinum chloride (Table , entry 11), but 70% conversion was obtained after 3 hours of reaction using the MoO 3 as catalyst (Table , entry 12). It is suggested that due to the existing electronic interaction between the pyridinum ion and [Mo 8 O 26 ] 4− component, the Lewis acid sites (Mo‐center) are effectively modified in this hybrid structure . A delay time in the oxidation of benzyl alcohol in the presence of 2,6‐di‐tert‐butyl‐4‐methylphenol as a radical scavenger also is a proof that our system proceeds via the free radical chain mechanism.…”

Scaled‐up, selective and green synthesis of sulfoxides under mild conditions using (CeIII‐MoVI)Ox/aniline hybrid rods as an efficient catalyst

“…[18][19][20][21][22][23][24][25] Moreover, overoxidation of the sulfoxides to sulfones is a common problem during the oxidation of sulfides [26,27] that has garnered attention from the synthetic community. [12,14,[46][47][48][49] In recent years, owing to the redox properties of ceria, various types of ceria-based catalysts including cerium (IV) triflate, [50] ammonium cerium (IV) nitrate, [51] immobilized cerium alkyl phosphonate [52] and heterobimetallic cerium (IV) oxo clusters [53] are also widely used in selective oxidation of sulfides. From an economical and environmental viewpoint, an acceptable process involving hydrogen peroxide (H 2 O 2 ) as a terminal oxidant in the presence of a catalyst would be at particular interest, [28,29] since hydrogen peroxide produces water as by-product and it is worth mentioning that a controlled partial oxidation is also dramatically easier than the most of other oxidants.…”

Green synthesis of 6-cyano-2,2-dimethyl-2-H-1-benzopyran and its subsequent enantioselective epoxidation

“…Complete characterization of the catalysts PMo 11 V and Py 3 -PMo 11 V was reported in a previous work [17,18]. Here, we present some relevant analysis of the catalysts in order to verify their characteristics.…”

“…The synthesis and full characterization of the PMo 11 V and Py 3 -PMo 11 V catalysts were reported in a previous work [17,18]. The SEM-EDAX analysis of heteropolyacid catalysts shows a homogeneous distribution of V, Mo, and P according to the expected percent atomic ratios.…”