H₂O₂-Oxidation of Alcohols Promoted by Polymeric Phosphotungstate Catalysts

Abstract

A novel polymeric phosphotungstate catalyst bearing a poly(ethylene oxide-pyridinium) matrix was developed that efficiently promoted oxidation of a variety of alcohols, including highly sterically demanding neopentyl alcohols, with hydrogen peroxide, to afford the corresponding carbonyl compounds in up to quantitative yield. The chemoselective oxidation of sterically hindered secondary alcohols in the presence of primary alcohols was achieved. The catalyst could be reused four times without any loss of catalytic activity.

A Highly Active and Reusable Self‐Assembled Poly(Imidazole/Palladium) Catalyst: Allylic Arylation/Alkenylation

“…Cinnamyl acetate (4 a; 88 mg, 0.5 mmol) was added to the reaction mixture, and the reaction vessel was then shaken using a PetiSyzer (HiPep Laboratories, Japan) at 50 8C for 4 h. The reaction mixture was filtered, and the recovered 3 was washed with Et 2 O (4 3 mL). The combined filtrate was dried over MgSO 4 under reduced pressure. The residue was chromatographed on silica gel (n-hexane/ethyl acetate 9:1) to give 6 a in 99 % yield.…”

“…We recently reported the preparation of highly active, reusable, heterogeneous polymeric metal catalysts for organic transformations, also known as molecular convolution, where a soluble linear polymer having multiple ligand groups is convoluted (noncovalently cross-linked) with transition metals through coordinative or ionic complexation. [4] We envisioned applying this concept to the preparation of metalloprotein-inspired polymeric imidazole metal catalysts to produce highly active, reusable, heterogeneous, selfassembled catalysts. Herein we report the development of a novel polymeric imidazole/acrylamide palladium catalyst that was utilized for the allylic arylation/alkenylation of allylic esters with aryl/alkenylboronic acids and tetraaryl borates.…”

Preparation, characterization and heterogeneous catalytic applications of GO/Fe3O4/HPW nanocomposite in chemoselective and green oxidation of alcohols with aqueous H2O2

“…The oxidation of alcohols in accordance with the principles of green chemistry is limited to some environmentally benign oxidants including hydrogen peroxide and molecular oxygen. Various methods that use hydrogen peroxide as oxidizing agents in the presence of heteropoly acids and polyoxometalates to oxidize primary and secondary alcohols to its corresponding carbonyl compounds have been reported in the literature . The mechanism of the effect of heteropoly acids and polyoxometalates is well known in catalyzing of oxidation reactions with hydrogen peroxide, and suggests the formation of an active species: Ishii–Venturello complex {PO 4 [WO(O 2 ) 2 ] 4 } 3– …”

Regenerating Spent Solutions of Vanadium‐containing Heteropoly Acids in the Presence of Additives

“…Despite a broad diversity of HPAs, the majority of stable budding catalysts for selective oxidation with oxygen or hydrogen peroxide belong to the Keggin H 3 XM 12 O 40 family (Figure ) . Recently, H 3 PW 12 O 40 ‐based and Bu 4 N[γ‐PW 10 O 38 V 2 (μ‐O)(μ‐OH)] compounds have been employed to catalyze the oxidation and hydroxylation of various substrates, including alkoxy‐ and alkylarenes, alkanes, alkenes, alcohols, and phenols in the presence of H 2 O 2 solution. Anthracene‐functionalized lacunary [SiW 11 O 39 ] 8– anion showed high activity for the aerobic light‐driven oxidation of alcohols into the corresponding aldehydes, whereas vanadium‐functionalized phosphotungstic H 3+ x PV x W 12– x O 40 acids were applied as photocatalysts for the oxidation of cyclohexane to cyclohexanone and also used in H 2 O 2 ‐based oxidation of alkanes and arenes .…”