Catalytic oxidation of anilines into azoxybenzenes on mesoporous silicas containing cobalt oxide

Chang, Ching-Fu; Liu, Shiuh‐Tzung

doi:10.1016/j.molcata.2008.10.032

Cited by 33 publications

(9 citation statements)

References 21 publications

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“…Normally, azoxyarenes are intermediates in this nitro- to aminoarene (aniline) transformation. They are important and useful organic products themselves, as they can be widely used in industry as dyes, polymerization inhibitors, reducing agents, chemical stabilizers, and important building blocks in many natural compounds and functional materials. − Azoxyarenes have been made through the selective reduction of nitroarenes or the selective oxidation of anilines. − Yet it is relatively uncommon for nitroarene reduction to stop at the azoxyarene intermediate step, making the Pd 2 Sn nanocrystals made here a much more interesting catalyst than we could have first envisioned, due to their catalytic activity and unique selectivity.…”

Section: Results and Discussionmentioning

confidence: 99%

“…89,90,91,92,93 Azoxyarenes have been made through the selective reduction of nitroarenes or the selective oxidative of anilines. 94,95,96,97,98 Yet it is relatively uncommon for nitroarene reduction to stop at the azoxyarene intermediate step, making the Pd2Sn nanocrystals made here a much more interesting catalyst than we could have first envisioned, due to their catalytic activity and unique selectivity.…”

Section: Lpdpr 3 L + Pd + Prmentioning

confidence: 99%

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Intermetallic Nanocatalysts from Heterobimetallic Group 10–14 Pyridine-2-thiolate Precursors

et al. 2020

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Intermetallic compounds are atomically ordered inorganic materials containing two or more transition metals and main-group elements in unique crystal structures. Intermetallics based on group 10 and group 14 metals have shown enhanced activity, selectivity, and durability in comparison to simple metals and alloys in many catalytic reactions. While high-temperature solid-state methods to prepare intermetallic compounds exist, softer synthetic methods can provide key advantages, such as enabling the preparation of metastable phases or of smaller particles with increased surface areas for catalysis. Here, we study a generalized family of heterobimetallic precursors to binary intermetallics, each containing a group 10 metal and a group 14 tetrel bonded together and supported by pincer-like pyridine-2-thiolate ligands. Upon thermal decomposition, these heterobimetallic complexes form 10-14 binary intermetallic nanocrystals. Experiments and density functional theory (DFT) computations help in better understanding the reactivity of these precursors toward the synthesis of specific intermetallic binary phases. Using Pd2Sn as an example, we demonstrate that nanoparticles made in this way can act as uniquely selective catalysts for the reduction of nitroarenes to azoxyarenes, which highlights the utility of the intermetallics made by our method. Employing heterobimetallic pincer complexes as precursors toward binary nanocrystals and other metal-rich intermetallics provides opportunities to explore the fundamental chemistry and applications of these materials.

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Section: Results and Discussionmentioning

confidence: 99%

Section: Lpdpr 3 L + Pd + Prmentioning

confidence: 99%

Intermetallic Nanocatalysts from Heterobimetallic Group 10–14 Pyridine-2-thiolate Precursors

et al. 2020

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“…Methodologies utilizing heterogeneous catalysts and hydrogen peroxide have been developed for the oxidation of aromatic amines. Examples include: rhenium, molybdenum, cobalt oxide, titanium silicate, Au/TiO 2 , Ag/WO 3 , CuCr 2 O 4 , dimeric [Ln 4 (H 2 O) 6 (b-GeW 10 O 38 ) 2 ] 12 − anions, titanium silicalite-1, titanium (IV) oxide and Cu-CeO 2 [6][7][8][9][10][11][12][13][14][15][16]. Although varying degrees of success in terms of substrate conversion and selectivity's have been achieved, there is clearly still a demand for reusable and efficient heterogeneous catalysts for the selective oxidation of anilines.…”

Section: Introductionmentioning

confidence: 99%

Low temperature liquid phase catalytic oxidation of aniline promoted by niobium pentoxide micro and nanoparticles

Ventura

Batalha

Fajardo

et al. 2017

Catalysis Communications

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“…Various types of molecular sieves , and mesoporous silica containing nanometric dispersed titanium oxide have been reported for the oxidation of aniline to azoxybenzene . It has been reported that mesoporous silicas containing cobalt oxide catalyst can be used for the selective oxidation of aniline to azoxybenzene using H 2 O 2 as the oxidant . Recently, Li et al reported synthesis of azobenzene using molecular oxygen in the liquid phase .…”

Section: Introductionmentioning

confidence: 99%

“…16 It has been reported that mesoporous silicas containing cobalt oxide catalyst can be used for the selective oxidation of aniline to azoxybenzene using H 2 O 2 as the oxidant. 17 Recently, Li et al reported synthesis of azobenzene using molecular oxygen in the liquid phase. 18 But in most of the cases, the recyclability of the catalysts and the product separation from the reaction mixtures become two major issues in liquid-phase reaction systems.…”

Section: ■ Introductionmentioning

confidence: 99%

Catalytic Oxidation of Aniline to Azoxybenzene Over CuCr₂O₄ Spinel Nanoparticle Catalyst

Acharyya

Ghosh

Bal

2014

ACS Sustainable Chem. Eng.

108

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Cationic surfactant cetyltrimethylammonium chloride-mediated hydrothermal preparation of CuCr 2 O 4 spinel nanoparticles has been reported. This CuCr 2 O 4 spinel nanoparticle catalyst has been characterized by XRD, XPS, SEM, TEM, TGA, and ICP-AES. Characterization results showed the formation of CuCr 2 O 4 spinel nanoparticles with sizes between 25 and 50 nm. It was found that the catalyst can selectively convert aniline to azoxybenzene with H 2 O 2 as oxidant. The effect of different reaction parameters like reaction temperature, H 2 O 2 to aniline molar ratio, reaction time, and so forth have been studied in detail. An aniline conversion of 78% with azoxybenzene selectivity of 92% can be achieved over this catalyst at 70 °C. The catalyst did not show any leaching up to five reuses, showing the true heterogeneity of the catalyst. However, significant H 2 O 2 decomposition occurs on the catalyst necessitating its usage in five-fold excess.

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Catalytic oxidation of anilines into azoxybenzenes on mesoporous silicas containing cobalt oxide

Cited by 33 publications

References 21 publications

Intermetallic Nanocatalysts from Heterobimetallic Group 10–14 Pyridine-2-thiolate Precursors

Intermetallic Nanocatalysts from Heterobimetallic Group 10–14 Pyridine-2-thiolate Precursors

Low temperature liquid phase catalytic oxidation of aniline promoted by niobium pentoxide micro and nanoparticles

Catalytic Oxidation of Aniline to Azoxybenzene Over CuCr₂O₄ Spinel Nanoparticle Catalyst

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Catalytic oxidation of anilines into azoxybenzenes on mesoporous silicas containing cobalt oxide

Cited by 33 publications

References 21 publications

Intermetallic Nanocatalysts from Heterobimetallic Group 10–14 Pyridine-2-thiolate Precursors

Intermetallic Nanocatalysts from Heterobimetallic Group 10–14 Pyridine-2-thiolate Precursors

Low temperature liquid phase catalytic oxidation of aniline promoted by niobium pentoxide micro and nanoparticles

Catalytic Oxidation of Aniline to Azoxybenzene Over CuCr2O4 Spinel Nanoparticle Catalyst

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Catalytic Oxidation of Aniline to Azoxybenzene Over CuCr₂O₄ Spinel Nanoparticle Catalyst