An Exceptionally Stable Ti Superoxide Radical Ion: A Novel Heterogeneous Catalyst for the Direct Conversion of Aromatic Primary Amines to Nitro Compounds

Dewkar, Gajanan K.; Nikalje, Milind D.; Ali, Iliyas Sayyed; Paraskar, Abhimanyu S.; Jagtap, H. S.; Sudalai, Arumugam

doi:10.1002/1521-3773(20010119)40:2<405::aid-anie405>3.0.co;2-6

Cited by 46 publications

(27 citation statements)

References 29 publications

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“…H 2 O 2 on titanium tetraalkoxide [Ti(OR) 4 ] in anhydrous methanol at 25°C in good yields (Scheme 1) [97][98][99][100].…”

Section: Catalyst Preparationmentioning

confidence: 99%

“…Remarkably, even aryl amines with electron withdrawing groups such as -NO 2 and -COOH are efficiently oxidized to the corresponding nitroarenes (entry 3 k and 3 l), which are difficult to obtain by conventional methods. It may be noted that zeolites such as TS-1, TS-2, NaY, CrS-2 and HY as heterogeneous catalysts are known to oxidize arylamines to azoxybenzene, azobenzene and nitrobenzene with poor selectivity [97]. Thus, aniline underwent oxidation with 50% aq.…”

Section: Oxidation Of N-h Bonds Of Amines: a High Yield Synthesis Of mentioning

confidence: 99%

“…6Attack of nitroso species on the electrophilic oxygen atom of the peroxide associated with the Ti matrix[97] Fig. 7 Proposed catalytic cycle for the oxidation of phenols[98] …”

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confidence: 99%

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A Novel Synthesis and Characterization of Titanium Superoxide and its Application in Organic Oxidative Processes

et al. 2010

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A novel, exceptionally stable titanium superoxide radical ion was prepared and its structure determined by FTIR, ESR, Raman spectroscopy, X-ray diffraction, thermogravimetric/differential thermal analysis and elemental analysis. This heterogeneous catalyst has been found to be effective for the selective oxidation of aromatic amines and phenols to the corresponding nitro aromatics and p-quinones, respectively. In addition, this non-toxic, inexpensive and reusable catalyst has also been used in aminobromination of olefins, which proceed to give the 1, 2-bromoaminated anti-Markovnikov product. A brief account of these results is summarized in this review.

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“…H 2 O 2 on titanium tetraalkoxide [Ti(OR) 4 ] in anhydrous methanol at 25°C in good yields (Scheme 1) [97][98][99][100].…”

Section: Catalyst Preparationmentioning

confidence: 99%

Section: Oxidation Of N-h Bonds Of Amines: a High Yield Synthesis Of mentioning

confidence: 99%

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A Novel Synthesis and Characterization of Titanium Superoxide and its Application in Organic Oxidative Processes

et al. 2010

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“…The TG curve of H 2 O 2 -treated anatase titania shows similar behavior as that of untreated one, but the exothermic peak in DTA at 632 K shows the loss of reactive oxygen from the surface of titania, which is absent in Ti-473 sample (figure 2b) [4].…”

Section: Powder Xrd and Tg-dtamentioning

confidence: 99%

“…These are not only chemically important but also biologically very interesting [1]. Literature reveals that titanium superoxide species are very stable in aqueous as well as in gel form [2][3][4]. Its unusual stability has lead to extensive studies on the formation and stabilization of reactive oxygen species on titania during the process of UV irradiation in presence of molecular oxygen [5], redox reactions involving use of hydrogen peroxide and Ti 3+ salts [6] and on titanium substituted molecular sieves [7][8][9].…”

Section: Introductionmentioning

confidence: 99%

Epoxidation of indene and cyclooctene on nanocrystalline anatase titania catalyst

2006

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Nanocrystalline anatase titania samples of different crystallite sizes were prepared by sol gel method using ultrasonication and calcination at different temperatures. The calcined samples were treated with H 2 O 2 in order to study the role of surface hydroxyl groups present on titania in generating reactive oxygen species responsible for the epoxidation reaction. The crystallite size of the calcined samples increased from 4 to 18 nm as the calcination temperature increased from 473 to 773 K, respectively. More uniform distribution/dispersion of the nanoparticles (SEM), marginally higher surface area, better thermal stability and phase purity are some of the advantages of preparation of nanocrystalline TiO 2 by using ultrasonication. EPR spectral data on the H 2 O 2 -treated samples confirmed the presence of superoxide radical species. The two distinct UV bands observed at 400 and 450 nm are assigned to charge transfer of peroxide (O 2 2) ) to Ti. FT-IR spectral data show that the surface hydroxyl groups are the active sites in the generation of reactive oxygen species. The catalytic activity was evaluated in a series of epoxidation reactions using indene and cyclooctene as substrates and aqueous H 2 O 2 as oxidant. The activity was found to decrease with increase in the calcination temperature of the samples, obviously due to an increase in crystallite size and a decrease in surface hydroxyl groups. The nanoparticle titania samples show better conversion and selectivity than the standard titania (Degussa P-25). The kinetic studies revealed that the reaction followed a pseudo first order kinetics in excess of H 2 O 2 .

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Titanium Tetraisopropoxide

Banwell¹,

García‐García²,

Aguilar³

2006

Encyclopedia of Reagents for Organic Synthesis

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An Exceptionally Stable Ti Superoxide Radical Ion: A Novel Heterogeneous Catalyst for the Direct Conversion of Aromatic Primary Amines to Nitro Compounds

Cited by 46 publications

References 29 publications

A Novel Synthesis and Characterization of Titanium Superoxide and its Application in Organic Oxidative Processes

A Novel Synthesis and Characterization of Titanium Superoxide and its Application in Organic Oxidative Processes

Epoxidation of indene and cyclooctene on nanocrystalline anatase titania catalyst

Titanium Tetraisopropoxide

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