Polyethylene Glycols as Efficient Catalysts for the Oxidation of Xanthine Alkaloids by Ceric Ammonium Nitrate in Acetonitrile: A Kinetic and Mechanistic Approach

Shylaja, S.; Rajanna, K. C.; Ramesh, K.; Reddy, K. Rajendar; Reddy, P. Giridhar

doi:10.1155/2013/835610

Cited by 10 publications

(4 citation statements)

References 38 publications

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“…However, the PEG chains in aqueous media are analogous to the structure of nonionic micelles of Triton-X and Tween 20. Consequently, the catalytic impact of PEGs on the kinetics of reactions could be explicated via the cooperative Piszkiewicz model [11,[19][20][21]. In this work, the model has been employed to investigate the effect of the presence of the very low concentrations of the polymers and surfactants in the reaction media through the interactions of the maltose molecules with the polymer or surfactant micelles to increase the concentration of maltose molecules inside the micelles, which behave as nanoreactors in the aqueous medium.…”

Section: Effect Of Saltsmentioning

confidence: 99%

“…Shylaja et al used PEGs to catalyze the reactions of some xanthine alkaloids with ceric ammonium nitrate to give uric acid derivatives. ey found that the rate of reaction increased linearly in the presence of a set of PEGs, and their catalytic activities depended on the nature as well as the molecular weight of the PEGs [11]. Likewise, PEGs catalyzed the reaction of borneol, isoborneol, and camphor with ceric ammonium nitrate acid-free conditions.…”

Section: Introductionmentioning

confidence: 96%

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The Catalytic Influence of Polymers and Surfactants on the Rate Constants of Reaction of Maltose with Cerium (IV) in Acidic Aqueous Medium

Dahadha

Hassan

Mfarej

et al. 2022

Journal of Chemistry

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Kinetics of the reaction of maltose with cerium ammonium sulfate were analyzed spectrophotometrically by observing the decrease of the absorbance of cerium (IV) at 385 nm in the presence and absence of polyethylene glycols (600, 1500, and 4000) and polyvinylpyrrolidone (PVP), in addition to anionic micelles of sodium dodecyl sulfate (SDS), cationic micelles of cetyltrimethylammonium bromide (CTAB) and non-ionic micelles of Tween 20 surfactants. Generally, there is little literature about using the polymers (PEGs and PVP) as catalysts in the oxidation-reduction reactions. Therefore, the major target of this work was to investigate the influence of the nature of polymers and surfactants on the oxidation rates of maltose by cerium (IV) in acidic aqueous media, as well as employing the Piszkiewicz model to explain the catalytic effect. The kinetic runs were derived by adaptation of the pseudo first-order reaction conditions with respect to the cerium (IV). The reaction was found to be first-order with respect to the oxidant and fractional-order to maltose and H2SO4. The reaction rates were enhanced in the presence of polymer and micellar catalysis. Indeed, the surfactants were found to work perfectly close to their critical micelle concentrations (CMC). Electrostatic interaction and H-bonding appear to play an influential role in binding maltose molecules to polymer/surfactant micelles, while oxidant ions remain at the periphery of the Stern layer within the micelle.

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Section: Effect Of Saltsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 96%

The Catalytic Influence of Polymers and Surfactants on the Rate Constants of Reaction of Maltose with Cerium (IV) in Acidic Aqueous Medium

Dahadha

Hassan

Mfarej

et al. 2022

Journal of Chemistry

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“…While PEO use is almost relegated to biomedical and healthcare applications [ 43 , 44 , 45 , 46 , 47 , 48 , 49 ], its usage in other fields is uncommon, such as in composite laminates for hindering delamination [ 36 ] and as phase change materials (PCMs) [ 50 ]. Even PEO application in catalysis is limited to a few reported cases [ 51 , 52 , 53 ]; however, it has never been shaped into nanofibers for catalytic purposes.…”

Section: Introductionmentioning

confidence: 99%

Water-Resistant Photo-Crosslinked PEO/PEGDA Electrospun Nanofibers for Application in Catalysis

et al. 2023

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Catalysts are used for producing the vast majority of chemical products. Usually, catalytic membranes are inorganic. However, when dealing with reactions conducted at low temperatures, such as in the production of fine chemicals, polymeric catalytic membranes are preferred due to a more competitive cost and easier tunability compared to inorganic ones. In the present work, nanofibrous mats made of poly(ethylene oxide), PEO, and poly(ethylene glycol) diacrylate, PEGDA, blends with the Au/Pd catalyst are proposed as catalytic membranes for water phase and low-temperature reactions. While PEO is a water-soluble polymer, its blending with PEGDA can be exploited to make the overall PEO/PEGDA blend nanofibers water-resistant upon photo-crosslinking. Thus, after the optimization of the blend solution (PEO molecular weight, PEO/PEGDA ratio, photoinitiator amount), electrospinning process, and UV irradiation time, the resulting nanofibrous mat is able to maintain the nanostructure in water. The addition of the Au6/Pd1 catalyst (supported on TiO2) in the PEO/PEGDA blend allows the production of a catalytic nanofibrous membrane. The reduction of 4-nitrophenol (4-NP) to 4-aminophenol (4-AP), taken as a water phase model reaction, demonstrates the potential usage of PEO-based membranes in catalysis.

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“…One of these polymeric materials is polyethylene glycol (PEG), which has attracted the attention of several researchers studying catalytic behaviour. 13,14 In this study, we investigated the kinetics of the permanganate ion oxidation of L-lysine in a perchloric acid medium. The reaction was already studied in an alkaline medium, where the product was reported to contain decarboxylated residue.…”

Section: Introductionmentioning

confidence: 99%

Micellar and Polymer Catalysis in the Kinetics of Oxidation of L-lysine by Permanganate Ion in Perchloric Acid Medium

Hassan¹,

Al-Dhoun²,

Batineh³

et al. 2021

S.Afr.j.chem.

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Kinetics of oxidation of L-lysine by permanganate ion in a perchloric acid medium was investigated to explore the order of the reaction with respect to oxidant and substrate and to study the catalytic behaviour of sodium lauryl sulphate (SLS) and polyethylene glycol (PEG). The reaction was found to be first-order with respect to the oxidant and the substrate and zero-order with respect to hydrogen ion. Changes in the sodium sulphate concentration produce a non-significant variation in the rate of the reaction. SLS and PEG were found to catalyze the reaction. Surfactant catalysis was modelled by Piszkiewicz's cooperativity model, while polymer catalysis was explained with the help of the Benesi-Hildebrand equation. The temperature dependence of the rate of the reaction was elucidated, and activation parameters were obtained. Interestingly, the reaction was found to possess positive activation entropy indicating the dissociative nature of the transition state and outer-sphere electron transfer mechanism. A mechanism of the reaction that is supported by the experimental findings was suggested. KEYWORDS L-lysine, permanganate ion, micellar catalysis, polymer catalysis, outer sphere electron transfer mechanism.

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Polyethylene Glycols as Efficient Catalysts for the Oxidation of Xanthine Alkaloids by Ceric Ammonium Nitrate in Acetonitrile: A Kinetic and Mechanistic Approach

Cited by 10 publications

References 38 publications

The Catalytic Influence of Polymers and Surfactants on the Rate Constants of Reaction of Maltose with Cerium (IV) in Acidic Aqueous Medium

The Catalytic Influence of Polymers and Surfactants on the Rate Constants of Reaction of Maltose with Cerium (IV) in Acidic Aqueous Medium

Water-Resistant Photo-Crosslinked PEO/PEGDA Electrospun Nanofibers for Application in Catalysis

Micellar and Polymer Catalysis in the Kinetics of Oxidation of L-lysine by Permanganate Ion in Perchloric Acid Medium

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