Efficient oxidation of arylmethylene compounds using nano-MnO2

Nammalwar, Baskar; Fortenberry, Chelsea; Bunce, Richard A.; Lageshetty, Sathish Kumar; Ausman, Kevin D.

doi:10.1016/j.tetlet.2013.02.009

Cited by 31 publications

(17 citation statements)

References 25 publications

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“…Several manganese oxides are known to function as “stoichiometric oxidants” for oxidation reactions accompanied by structural change. Once the structure changes into a redox inactive phase during the reaction, the generation of the product is suppressed significantly, and severe deactivation is observed if we use the recovered catalyst for reuse experiments . To investigate whether the formation of 2 a in the presence of Ni‐MnO x was caused by “aerobic oxidation catalysis” or “stoichiometric oxidation”, the reaction was performed under nonaerobic conditions (Ar atmosphere).…”

Section: Resultsmentioning

confidence: 99%

“…(2) Incorporation of additional metals into the manganese oxide structure is important to increase the redox stability. Several manganese oxides are susceptible to reduction; once such manganese oxides are reduced by substrates, their reoxidation by O 2 is quite difficult, which leads to the formation of redox inactive species . Recently, we reported that manganese oxides with additional metals in their structures, such as K‐containing tunnel manganese oxide (α‐MnO 2 , K‐OMS‐2) and K‐containing layered manganese oxide (δ‐MnO 2 ), exhibit a high catalytic performance for several aerobic oxidation reactions and maintain their crystal structures after their use for oxidation reactions even under nonaerobic conditions, unlike manganese oxides that contain no additional metals such as β‐MnO 2 and γ‐MnO 2 .…”

Section: Introductionmentioning

confidence: 99%

“…Manganese oxidesh ave attracted tremendousr esearch interest because of their potentialu se as electrode materials, adsorbents, oxidants, catalysts, and catalysts upports. [16][17][18][19][20][21][22][23][24] In particular,t heir oxidation catalysis is of great interest, and thus numerousa erobic oxidation systemst hat use catalysts based on manganese oxide have been developed. [25][26][27][28][29][30][31][32][33][34][35][36][37][38][39] As fora lkylarene oxygenation, several catalysts based on manganese oxide have also been reported to be highly effective (Table S2); [40][41][42][43][44] for example, Hara and colleagues reported recently that nanosized hexagonal SrMnO 3 perovskite exhibits ah igh catalytic performance for alkylarene oxygenation under relatively mild conditions (60-120 8C, 1atm O 2 ,n oa dditives).…”

Section: Introductionmentioning

confidence: 99%

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Aerobic Oxygenation of Alkylarenes over Ultrafine Transition‐Metal‐Containing Manganese‐Based Oxides

et al. 2018

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The oxygenation of alkylarenes to the corresponding aryl ketones is an important reaction, and the development of efficient heterogeneous catalysts that can utilize O2 as the sole oxidant is highly desired. In this study, we developed an efficient alkylarene oxygenation process catalyzed by ultrafine transition‐metal‐containing Mn‐based oxides with spinel or spinel‐like structures (M‐MnOx, M=Fe, Co, Ni, Cu). These M‐MnOx catalysts were prepared by a low‐temperature reduction method in 2‐propanol‐based solutions using tetra‐n‐butyl ammonium permanganate (TBAMnO4) as the Mn source, and they exhibited high Brunauer–Emmett–Teller surface areas (typically >400 m2 g−1). Using fluorene as the model substrate, the catalytic activities of M‐MnOx and Mn3O4 were compared. The catalytic activities of M‐MnOx were significantly higher than that of Mn3O4, which demonstrates that the incorporation of transition metals in manganese oxide was critical. Among the series of M‐MnOx catalysts examined, Ni‐MnOx exhibited the highest catalytic activity for the oxygenation. In addition, the catalytic activity of Ni‐MnOx was higher than that of a physical mixture of Mn3O4 and NiO. Furthermore, Ni‐MnOx exhibited a broad substrate scope with respect to various types of structurally diverse (hetero)alkylarenes (16 examples). The observed catalysis was truly heterogeneous, and the Ni‐MnOx catalyst was reusable for the oxygenation of fluorene at least three times and its high catalytic performance was preserved, for example, the reaction rate, final product yield, and product selectivity. The present Ni‐MnOx‐catalyzed oxygenation process is possibly initiated by a single‐electron oxidation process, and herein a plausible oxygen‐transfer mechanism is proposed based on several pieces of experimental evidence.

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Section: Resultsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Aerobic Oxygenation of Alkylarenes over Ultrafine Transition‐Metal‐Containing Manganese‐Based Oxides

et al. 2018

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“…It should be noted that Na 2 S 2 O 3 was dosed soon after the 5-min rapid mixing period to quench the residual KMnO 4 to MnO 2 . The freshly prepared in-situ MnO 2 is a solid oxidant and is widely used for the oxidation of arylmethylene compounds, pyrene, sulfadiazine and arsenite (Dong et al, 2009;Li et al, 2010;Chien et al, 2011;Nammalwar et al, 2013). However, the in-situ MnO 2 showed little oxidative efficacy towards algae cells and caused little damage to algae cells even at doses as high as 120 mM.…”

Section: Effects Of Kmno 4 Doses On M Aeruginosa Cell Integritymentioning

confidence: 99%

KMnO 4 –Fe(II) pretreatment to enhance Microcystis aeruginosa removal by aluminum coagulation: Does it work after long distance transportation?

Lan

Miao

et al. 2016

Water Research

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a b s t r a c tKMnO 4 eFe(II) pretreatment was proposed to enhance Microcystis aeruginosa (M. aeruginosa) removal by aluminum (Al) coagulation in drinking water treatment plants (DWTPs) in our previous study. This study aims to optimize this process and evaluate the feasibility of using the process at water sources, which are usually far away from DWTPs. The optimum molar ratio of KMnO 4 to Fe(II) ½R KMnO4:FeðIIÞ is observed to be 1:3 with respect to algae removal and residual manganese (Mn) control. As indicated from flow cytometer analysis, KMnO 4 at <20 mM promisingly maintains cell integrity, with damaged cell ratios of below 10%. KMnO 4 at 30 and 60 mM damages M. aeruginosa cells more significantly and the damaged cell ratios increase to 21% and 34% after 480 min. The intracellular organic matter (IOM) release can be controlled by the subsequent introduction of Fe(II) to quench residual KMnO 4 . KMnO 4 eFe(II) pretreatment at the KMnO 4 dose of 10 mM dramatically enhances the algae removal by over 70% compared to that by Al coagulation, even if KMnO 4 and Fe(II) are introduced 480 min prior to the addition of Al 2 (SO 4 ) 3 . The Al doses can be reduced by more than half to achieve the same algae removal. Furthermore, the deposition of the tiny FeeMn precipitates formed rarely occurs, as indicated by a settleability evaluation prior to Al addition. The KMnO 4 eFe(II) process can be sequentially dosed at intake points in water sources to achieve moderate inactivation of algae cells and to enhance algae removal in DWTPs thereafter.

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“…An oxidant is required to provide an oxygen source and transfer oxygen to the olefin in the course of the reaction; however, the use of oxidants such as H 2 O 2 , PhIO, t-BuOOH and CrO 3 entails the formation of dangerous residues which are not only difficult to process but also harmful to the environment (Nammalwar et al, 2013;Titinchi & Abbo, 2013;Xu et al, 2012;Yang et al, 2009a). Nowadays, since the concept of environmental protection has become more and more important in the field of chemical research, molecular oxygen attracts more attention from chemists.…”

Section: Introductionmentioning

confidence: 99%

Carbonylation of cyclohexene to 2-cyclohexene-1-one by montmorillonite-supported Co(II) catalysts

2015

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A novel environmentally-friendly catalytic system for the carbonylation of cyclohexene with molecular oxygen under conditions of mild temperature, and under an atmospheric oxygen pressure is presented. In this system, a series of readily-prepared cobalt complexes of 2-aminophenol and its derivatives immobilised onto montmorillonite were used as catalysts. The catalysts were characterised by FT-IR, elemental analysis, thermogravimetric analysis, powder X-ray diffraction, diffuse reflectance ultraviolet visible spectra, scanning electron microscopic measurements, transmission electron microscopic measurements and the Brunauer-Emmett-Teller method. The effects of various reaction conditions such as catalyst dosage, temperature and time were optimised, obtaining an 88.7 % conversion with 72.0 % selectivity of 2-cyclohexene-1-one in 6 h. The results show that the catalytic activity of the cobalt complexes encapsulated in montmorillonite is higher than those of the free complexes. In addition, the heterogeneous catalysts were stable and can be recycled up to five times without any noticeable change in the catalytic activity.

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Efficient oxidation of arylmethylene compounds using nano-MnO2

Cited by 31 publications

References 25 publications

Aerobic Oxygenation of Alkylarenes over Ultrafine Transition‐Metal‐Containing Manganese‐Based Oxides

Aerobic Oxygenation of Alkylarenes over Ultrafine Transition‐Metal‐Containing Manganese‐Based Oxides

KMnO 4 –Fe(II) pretreatment to enhance Microcystis aeruginosa removal by aluminum coagulation: Does it work after long distance transportation?

Carbonylation of cyclohexene to 2-cyclohexene-1-one by montmorillonite-supported Co(II) catalysts

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