Oxidation of diphenylamine to diphenylnitroxide in faujasite zeolite studied by electron paramagnetic resonance

Borkowski, R. P.; Doetschman, David C.; Fox, Jack D.; Gargossian, C.

doi:10.1016/s0167-2738(97)00346-9

Cited by 8 publications

(6 citation statements)

References 17 publications

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“…The halocarbon guest samples were utilized as received. NaX faujasite characterization was performed via powder X-ray diffraction, X-ray elemental, and differential thermal analyses as reported in a previous work . The X-ray elemental analysis results of the characterization produce the dehydrated unit cell formula Na 82 (SiO 2 ) 110 (AlO 2 ) 82 with Si/Al = 1.34, consistent with an X-type faujasite unit cell.…”

Section: Methodsmentioning

confidence: 88%

Effects of tert-Butyl Halide Molecular Siting in Crystalline NaX Faujasite on The Infrared Vibrational Spectra

Fox

Meenakshi

2005

J. Phys. Chem. B

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Experimental, analytical, and modeling techniques employed in this study elucidate interactions between adsorbate molecules and the interior surfaces of the porous host faujasite. The vibrational spectroscopies of guest and host offer opportunities to locate the guest site in the host. We present Fourier transform (FT) infrared (IR) studies of sodium-X (NaX) faujasite supercage-included tert-butyl halides, (CH(3))(3)C-X (X=Cl, Br, I) in comparison with the adsorbate molecular gas-phase and host solid-state spectra at 295 K. Four observations of guest (nu(5,) nu(6), nu(7), and {nu(3), nu(16), nu(17)}) vibrational mode changes, three of them concomitant with host mode changes, together with modeling studies, point to a particular preferred siting of the guest molecules at host hexagonal prisms (D6R). The siting involved simultaneous interactions of the host with methyl group axial protons and the halide atom. All three methyl group axial protons interact preferentially with a single D6R O1 oxygen atom via C-H...O bonding. The halide atom also interacts with a site III' Na cation. The cation, in turn, is coordinated by three O atoms (two O1 and an O4). Two of these O atoms (O1) bridge the double six-rings that form the hexagonal prism part of the NaX substructure. O4 connects the two D6R units.

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Section: Methodsmentioning

confidence: 88%

Effects of tert-Butyl Halide Molecular Siting in Crystalline NaX Faujasite on The Infrared Vibrational Spectra

Fox

Meenakshi

2005

J. Phys. Chem. B

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“…KX is a more favorable host for this oxidation than either Li + and Na + or Rb + and Cs + -exchanged X. A weak ESR triplet led the authors to propose O 2 preactivation by simultaneous interaction with the zeolite Lewis sites and the hydrogen atom of 60 , followed by a concerted rearrangement to 62 • and hydroxyl radical . No evidence for 60 •+ was observed in agreement with the fact that alkali-exchanged X zeolites are basic rather than acid solids.…”

Section: Va8 Radical Cations Of Nitrogen-containing Substratesmentioning

confidence: 90%

“…The oxidation of 60 to 62 • in a series of alkali-exchanged X faujasites was followed by ESR . KX is a more favorable host for this oxidation than either Li + and Na + or Rb + and Cs + -exchanged X.…”

Section: Va8 Radical Cations Of Nitrogen-containing Substratesmentioning

confidence: 99%

Generation and Reactions of Organic Radical Cations in Zeolites

2002

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“…More recently, the conversion of DPA into on alkali DPNOm etal ion exchanged Y zeolites has been studied by EPR. 23 As for the putative incorporation of TPA, model considerations show clearly that its signiÐcant three-directional extension (D13 should preclude it from entering through the A ) narrow access channels (D7. 4 into the Y faujasite A ) "" supercavities ÏÏ.10 In the light of these considerations, the reported EPR spectrum must be ascribed to minor quantities of radical cations adsorbed on the external surface of Yzeolite, probably formed at the entrance of the pores as was later proposed.10 Of course, the large a-cages of Y faujasite accommodate species as large as the triphenylpyrylium ion ;18 thus, they surely can accommodate TPA (if it could get inside).…”

Section: Discussionmentioning

confidence: 99%

Generation and conversions of aromatic amine radical cations in acid zeolites

Garcı́a

Martí

Casades

et al. 2001

Phys. Chem. Chem. Phys.

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Incorporation of aromatic amines, including diphenylamine (DPA), carbazole (Cbz), diphenylbenzidine (DPB) and benzidine (Bzd), into acid zeolites generated the corresponding radical cations, and DPA~`, Cbz~`, DPB~à s indicated by comparison of the characteristic long-wavelength di †use reÑectance spectra with spectra Bzd~`, observed in solution. Samples of sequestered in HZSM-5 are deprotonated ; the resulting DPA~d iphenylaminyl radical, is remarkably stable ; di †use reÑectance or EPR spectra show that a signiÐcant DPN~, population persists for longer than four years. In contrast, adsorbed within HY zeolite, undergoes a DPA~c lean conversion to Non-acidic zeolites devoid of and Lewis sites failed to generate radical Cbz~`. B r Ônsted cations to an extent detectable spectroscopically ; these results clearly indicate that and/or Lewis sites BrÔnsted are responsible for the observed oxidation.

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Oxidation of diphenylamine to diphenylnitroxide in faujasite zeolite studied by electron paramagnetic resonance

Cited by 8 publications

References 17 publications

Effects of tert-Butyl Halide Molecular Siting in Crystalline NaX Faujasite on The Infrared Vibrational Spectra

Effects of tert-Butyl Halide Molecular Siting in Crystalline NaX Faujasite on The Infrared Vibrational Spectra

Generation and Reactions of Organic Radical Cations in Zeolites

Generation and conversions of aromatic amine radical cations in acid zeolites

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