Simple Heteropoly Acids as Water-Tolerant Catalysts in the Oxidation of Alcohols with 34% Hydrogen Peroxide, A Mechanistic Approach

doi:10.5012/jkcs.2008.52.1.023

Cited by 19 publications

(1 citation statement)

References 33 publications

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“…(TBA) 7 PW 11 O 39 was prepared by the method described in the literature [27]. A 15.00 g quantity of H 3 PW 12 O 40 ·14H 2 O was dissolved in 20.0 mL of water; a 5.0 g quantity of [(n-C 4 H 9 ) 4 N]Br (TBABr) was dissolved in 50.0 mL of CH 2 Cl 2 .…”

Section: Preparation Of Catalystsmentioning

confidence: 99%

Dehydrocyclization of n-Hexane over Heteropolyoxometalates Catalysts

Eid¹,

Benlounes²,

Hilal³

et al. 2013

ACES

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The catalytic dehydrocyclization of n-hexane was studied here for the first time using a number of compounds based on H₃PMo₁₂O₄₀. The described catalystswere prepared by either replacing the acidic proton with counter-ions such as ammonium or transition metal cations (NH₄⁺, Fe³⁺, K⁺), or by replacing Mo⁶⁺ with (Ni³⁺, Co³⁺, Mn³⁺) in the polyoxometalate framework, as reported earlier. For comparison purposes, the known (TBA)₇PW₁₁O₃₉ catalyst system was used. All reactions were conducted at different temperatures in the range 200 - 450. The Keggin structure of these heteropolycompounds was ascertained by XRD, UV and IR measurements. ³¹P NMR measurements and thermal behaviour of the prepared catalystswere also studied. These modified polyoxometalates exhibited heterogeneous superacidic catalytic activities in dehydrocyclization of n-hexane into benzene, cyclohexane, cyclohexene and cyclohexadiene. The catalysts obtained by substituting the acidic proton or coordination atom exhibited higher selectivity and stability than the parent compound H₃PMo₁₂O₄₀. Catalytic activity and selectivity were heavily dependent on the composition of the catalyst and on the reaction conditions. At higher temperatures, the catalyst exhibited higher conversion efficiency at the expense of selectivity. Using higher temperatures (>400) in the presence of hydrogen carrier gas, selectivity towards dehydrocyclization ceased and methane dominated. To explain the results, a plausible mechanism is presented, based on super-acidic nature of the catalyst systems.

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Section: Preparation Of Catalystsmentioning

confidence: 99%

Dehydrocyclization of n-Hexane over Heteropolyoxometalates Catalysts

Eid¹,

Benlounes²,

Hilal³

et al. 2013

ACES

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Mild and Efficient Catalytic Protocol for Tetrahydropyranylation of Alcohols Using Acidic Keggin and Wells‐Dawson Structures

Tayebee

2008

Chin. J. Chem.

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A simple, mild and effective procedure is reported to the generation of 2‐tetrahydropyranyl acetals from alcohols. Keggin and Wells‐Dawson heteropolyoxometalates were used as catalysts at ambient temperature in acetone as solvent with good yields and high selectivities in a short reaction time. Different reaction parameters affecting efficiency of the protocol were also studied. The use of these acid catalysts allows replacing the usual soluble inorganic acids, contributing to waste reduction.

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An efficient and green synthetic protocol for the preparation of bis(indolyl)methanes catalyzed by H6P2W18O62·24H2O, with emphasis on the catalytic proficiency of Wells-Dawson versus Keggin heteropolyacids

Tayebee

Nehzat

Rezaei‐Seresht

et al. 2011

Journal of Molecular Catalysis A: Chemical

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Simple Heteropoly Acids as Water-Tolerant Catalysts in the Oxidation of Alcohols with 34% Hydrogen Peroxide, A Mechanistic Approach

Abstract: may be used as a simple, effective, and cheap catalyst for this type of transformation in normal drinking water with excellent yields. Effects of different solvents at 25-80 o C and changing concentration of catalyst and substrate on the reaction progress were also studied.

Cited by 19 publications

References 33 publications

Dehydrocyclization of n-Hexane over Heteropolyoxometalates Catalysts

Dehydrocyclization of n-Hexane over Heteropolyoxometalates Catalysts

Mild and Efficient Catalytic Protocol for Tetrahydropyranylation of Alcohols Using Acidic Keggin and Wells‐Dawson Structures

An efficient and green synthetic protocol for the preparation of bis(indolyl)methanes catalyzed by H6P2W18O62·24H2O, with emphasis on the catalytic proficiency of Wells-Dawson versus Keggin heteropolyacids

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