Ultraviolet Absorption Determination of Nitrogen Dioxide

Norris, M. S.; Fleck, Sabine; Lichtenfels, D. H.

doi:10.1021/ac60106a019

Cited by 9 publications

(7 citation statements)

References 5 publications

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“…The band position, shape, and fine structure are all very similar to that observed for NO 2 spectra in the gas phase. [42][43][44][45] However, these spectra do not correspond to NO 2 only. A distinct set of small peaks, whose relative contribution to the measured absorbance changes with temperature and pressure, can be seen on top of the large NO 2 band.…”

Section: Resultsmentioning

confidence: 97%

“…Their concentrations, however, could not be determined directly, since their extinction coefficients are unknown under hydrothermal conditions. The NO 2 extinction coefficients in the gas phase have been determined accurately − ,− and are strongly dependent upon temperature. , The NO 2 band fine structure is significantly reduced in SCW, especially at higher densities (see above). Data are unavailable for nitrous acid extinction coefficients versus temperature, most likely due to the low stability of the acid at low temperatures.…”

Section: Resultsmentioning

confidence: 98%

“…Their concentrations, however, could not be determined directly, since their extinction coefficients are unknown under hydrothermal conditions. The NO 2 extinction coefficients in the gas phase have been determined accurately [43][44][45][68][69][70][71] and are strongly dependent upon temperature. 45,70 The NO 2 band fine structure is significantly reduced in SCW, especially at higher densities (see above).…”

Section: Resultsmentioning

confidence: 99%

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Nitric/Nitrous Acid Equilibria in Supercritical Water

et al. 1999

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UV−vis spectroscopy was utilized to measure the decomposition of aqueous HNO3 solutions above 300 °C, in some cases with added NaOH, H2O2, and/or NaNO2, to form NO2, HNO2, NO, N2O, and oxygen. Individual bands corresponding to HNO2 and NO2 were deconvoluted from the spectra up to 400 °C. With constrained nonlinear optimization, areas of these bands were used to determine extinction coefficients of NO2 and HNO2 and equilibrium constants for the reactions: HNO3 ⇌ H+ + NO3 -; 2HNO3 ⇌ H2O + 2NO2 + (1/2)O2; 2NO2 + H2O ⇌ HNO3 + HNO2; 2HNO2 ⇌ H2O + 2NO + (1/2)O2; 2NO ⇌ N2O + (1/2)O2; (Na+)(NO3 -) ⇌ Na+ + NO3 -.

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Section: Resultsmentioning

confidence: 97%

Section: Resultsmentioning

confidence: 98%

“…Their concentrations, however, could not be determined directly, since their extinction coefficients are unknown under hydrothermal conditions. The NO 2 extinction coefficients in the gas phase have been determined accurately [43][44][45][68][69][70][71] and are strongly dependent upon temperature. 45,70 The NO 2 band fine structure is significantly reduced in SCW, especially at higher densities (see above).…”

Section: Resultsmentioning

confidence: 99%

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Nitric/Nitrous Acid Equilibria in Supercritical Water

et al. 1999

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“…After the period, the nitrogen dioxide gas was evolved, which was confirmed by UV/Vis spectroscopy according to ref. 18. Without [H 4 PVMo 11 O 40 ], no evolution of nitrogen dioxide was observed and the nitration did not proceed.…”

Section: Resultsmentioning

confidence: 99%

Nitration of Alkanes with Nitric Acid by Vanadium‐Substituted Polyoxometalates

Shinachi

Yahiro

Yamaguchi

et al. 2004

Chemistry A European J

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The nitration of alkanes by using nitric acid as a nitrating agent in acetic acid was efficiently promoted by vanadium-substituted Keggin-type phosphomolybdates such as [H4PVMo11O40], [H5PV2Mo10O40], and [H6PV3Mo9O40] as catalyst precursors. A variety of alkanes including alkylbenzenes were nitrated to the corresponding nitroalkanes as major products in moderate yields with formation of oxygenated products under mild reaction conditions. The carbon--carbon bond cleavage reactions hardly proceeded. ESR, NMR, and IR spectroscopic data show that the vanadium-substituted polyoxometalate, for example, [H4PVMo11O40], decomposes to form free vanadium species and [PMo12O40](3-) Keggin anion. The reaction mechanism involving a radical-chain path is proposed. The polyoxometalates initially abstract the hydrogen of the alkane to form the alkyl radical and the reduced polyoxometalates. The reduced polyoxometalates subsequently react with nitric acid to produce the oxidized form and nitrogen dioxide. This step would be promoted mainly by the phosphomolybdates, [PMo12O40](n-), and the vanadium cations efficiently enhance the activity. The nitrogen dioxide promotes the further formation of nitrogen dioxide and an alkyl radical. The alkyl radical is trapped by nitrogen dioxide to form the corresponding nitroalkane.

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“…La deviation moyenne de +lo% pour les 16 melanges utilisCs pour la calibration est lkghrement superieure A la deviation de +8% publiile par Norris (10). Les fluctuations ICgPres de tempbrature entre le m6lange e t 116chantillonnage peuvent expliquer cette difference.…”

Section: Introductionunclassified

l'OXYDATION Stoïchiométrique De l'OXYDE d'AZOTE Par l'OZONE Établie Par Photométrie Du Bioxyde d'AZOTE

Goyer¹

1956

Can. J. Chem.

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Ultraviolet Absorption Determination of Nitrogen Dioxide

Cited by 9 publications

References 5 publications

Nitric/Nitrous Acid Equilibria in Supercritical Water

Nitric/Nitrous Acid Equilibria in Supercritical Water

Nitration of Alkanes with Nitric Acid by Vanadium‐Substituted Polyoxometalates

l'OXYDATION Stoïchiométrique De l'OXYDE d'AZOTE Par l'OZONE Établie Par Photométrie Du Bioxyde d'AZOTE

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