Kinetics of <i>n</i>-Butoxy and 2-Pentoxy Isomerization and Detection of Primary Products by Infrared Cavity Ringdown Spectroscopy

Sprague, Matthew K.; Garland, Eva R.; Mollner, Andrew K.; Bloss, C.; Bean, Brian D.; Weichman, Marissa L.; Mertens, Laura A.; Okumura, Mitchio; Sander, Stanley P.

doi:10.1021/jp212136r

Cited by 9 publications

(19 citation statements)

References 90 publications

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“…The rate coefficient for isomerization of n -C 4 H 9 O is sufficiently higher, k n7 (760) = 1.8 × 10 5 s –1 , as obtained by averaging the results from the recent PLP-CRDS study of Sprague et al and the studies referenced herein. It is necessary to note that the k n7 values were determined from the relative k n7 / k n5 measurements, assuming k n5 = 9.5 × 10 –15 cm 3 molecule –1 s –1 for the reference reaction with oxygen recommended by Atkinson, which seems to be more reliable than the more recent recommendation of 1.4 × 10 –14 cm 3 molecule –1 s –1 , as the latter is based on the results of Morabito and Heicklen extracted from the relative k n5 / k n6 measurements using an early generic k n6 value of 4.4 × 10 –11 cm 3 molecule –1 s –1 , while new results give k n6 = 3.2 × 10 –11 cm 3 molecule –1 s –1 .…”

Section: Experimental Methodssupporting

confidence: 53%

Pressure Dependence of Butyl Nitrate Formation in the Reaction of Butylperoxy Radicals with Nitrogen Oxide

et al. 2014

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The yield of 1- and 2-butyl nitrates in the gas-phase reactions of NO with n-C4H9O2 and sec-C4H9O2, obtained from the reaction of F atoms with n-butane in the presence of O2, was determined over the pressure range of 100-600 Torr at 298 K using a high-pressure turbulent flow reactor coupled with a chemical ionization quadrupole mass spectrometer. The yield of butyl nitrates was found to increase linearly with pressure from about 3% at 100 Torr to about 8% at 600 Torr. The results obtained are compared with the available data concerning nitrate formation from NO reaction with other small alkylperoxy radicals. These results are also discussed through the topology of the lowest potential energy surface mainly obtained from DFT(B3LYP/aug-cc-pVDZ) calculations of the RO2 + NO reaction paths. The formation of alkyl nitrates, due essentially to collision processes, is analyzed through a model that points out the pertinent physical parameters of this system.

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Section: Experimental Methodssupporting

confidence: 53%

Pressure Dependence of Butyl Nitrate Formation in the Reaction of Butylperoxy Radicals with Nitrogen Oxide

et al. 2014

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“…In a new variation on the cavity ring-down approach, Okumura and co-workers 36 have detected hydroxyl-peroxy radicals in the OH fundamental stretching region. The radicals were formed following the isomerization of C4 and C5 alkoxy radicals, followed by addition of O 2 to the resultant hydroxyalkyl radicals.…”

Section: Advances In the Detection Of Peroxy Radicalsmentioning

confidence: 99%

Laboratory studies of organic peroxy radical chemistry: an overview with emphasis on recent issues of atmospheric significance

2012

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Organic peroxy radicals (often abbreviated RO(2)) play a central role in the chemistry of the Earth's lower atmosphere. Formed in the atmospheric oxidation of essentially every organic species emitted, their chemistry is part of the radical cycles that control the oxidative capacity of the atmosphere and lead to the formation of ozone, organic nitrates, organic acids, particulate matter and other so-called secondary pollutants. In this review, laboratory studies of this peroxy radical chemistry are detailed, as they pertain to the chemistry of the atmosphere. First, a brief discussion of methods used to detect the peroxy radicals in the laboratory is presented. Then, the basic reaction pathways - involving RO(2) unimolecular reactions and bimolecular reactions with atmospheric constituents such as NO, NO(2), NO(3), O(3), halogen oxides, HO(2), and other RO(2) species - are discussed. For each of these reaction pathways, basic reaction rates are presented, along with trends in reactivity with radical structure. Focus is placed on recent advances in detection methods and on recent advances in our understanding of radical cycling processes, particularly pertaining to the complex chemistry associated with the atmospheric oxidation of biogenic hydrocarbons.

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“…We detected intermediates and primary products by IR-CRDS, with 10 μs temporal resolution. Our PLP-IR-CRDS apparatus has been described in detail elsewhere; , here, we present a brief overview of the apparatus. A schematic of the laser system can be found in the Supporting Information.…”

Section: Experimental Sectionmentioning

confidence: 99%

“…We have shown that pulsed Infrared cavity ringdown spectroscopy (IR-CRDS) provides a sensitive means for the selective detection of transient intermediates in the mid-IR, especially in the OH stretch region. We have detected reactive intermediates and primary products of free radical reactions in time-resolved flow cell experiments, including the initial HOONO and HONO 2 products formed from the reaction of • OH + NO 2 • , and the 4,1-hydroxy-butyl and 4,1-hydroxy-butyl-peroxy radicals formed from the isomerization of the n- butoxy radical. − …”

Section: Introductionmentioning

confidence: 99%

Cavity Ringdown Spectroscopy of the Hydroxy-Methyl-Peroxy Radical

et al. 2013

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We report vibrational and electronic spectra of the hydroxy-methylperoxy radical (HOCH 2 OO • or HMP), which was formed as the primary product of the reaction of the hydroperoxy radical, HO 2• , and formaldehyde, HCHO. The ν 1 vibrational (OH stretch) spectrum and the A ̃← X ̃electronic spectrum of HMP were detected by infrared cavity ringdown spectroscopy (IR-CRDS), and assignments were verified with density functional calculations. The HMP radical was generated in reactions of HCHO with HO 2• . Free radical reactions were initiated by pulsed laser photolysis (PLP) of Cl 2 in the presence of HCHO and O 2 in a flow reactor at 300−330 Torr and 295 K. IR-CRDS spectra were measured in mid-IR and near-IR regions over the ranges 3525−3700 cm −1 (ν 1 ) and 7250−7800 cm −1 (A ̃← X ) respectively, at a delay time 100 μs after photolysis. The ν 1 spectrum had an origin at 3622 cm −1 and exhibited partially resolved P-and R-branch contours and a small Q-branch. At these short delay times, spectral interference from HOOH and HCOOH was minimal and could be subtracted. From B3LYP/6-31+G(d,p) calculations, we found that the anharmonic vibrational frequency and band contour predicted for the lowest energy conformer, HMP-A, were in good agreement with the observed spectrum. In the near-IR, we observed four well spaced vibronic bands, each with partially resolved rotational contours. We assigned the apparent origin of the A ̃← X ̃electronic spectrum of HMP at 7389 cm −1 and two bands to the blue to a progression in ν 15 ′, the lowest torsional mode of the A ̃state (ν 15 ′ = 171 cm −1 ). The band furthest to the red was assigned as a hot band in ν 15 ″, leading to a ground state torsional frequency of (ν 15 ″ = 122 cm −1 ). We simulated the spectrum using second order vibrational perturbation theory (VPT2) with B3LYP/6-31+G(d,p) calculations at the minimum energy geometries of the HMP-A conformer on the X ̃and A ̃states. The predictions of the electronic origin frequency, torsional frequencies, anharmonicities, and rotational band contours matched the observed spectrum. We investigated the torsional modes more explicitly by computing potential energy surfaces of HMP as a function of the two dihedral angles τ HOCO and τ OOCO . Wave functions and energy levels were calculated on the basis of this potential surface; these results were used to calculate the Franck−Condon factors, which reproduced the vibronic band intensities in the observed electronic spectrum. The transitions that we observed all involved states with wave functions localized on the minimum energy conformer, HMP-A. Our calculations indicated that the observed near-IR spectrum was that of the lowest energy X ̃state conformer HMP-A, but that this conformer is not the lowest energy conformer in the A ̃state, which remains unobserved. We estimated that the energy of this lowest conformer (HMP-B) of the A ̃state is E 0 (A , HMP-B) ≈ 7200 cm −1 , on the basis of the energy difference E 0 (HMP-B) − E 0 (HMP-A) on the A ̃state computed at the B3LYP/6-31+G(d,p) level.

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Kinetics of n-Butoxy and 2-Pentoxy Isomerization and Detection of Primary Products by Infrared Cavity Ringdown Spectroscopy

Cited by 9 publications

References 90 publications

Pressure Dependence of Butyl Nitrate Formation in the Reaction of Butylperoxy Radicals with Nitrogen Oxide

Pressure Dependence of Butyl Nitrate Formation in the Reaction of Butylperoxy Radicals with Nitrogen Oxide

Laboratory studies of organic peroxy radical chemistry: an overview with emphasis on recent issues of atmospheric significance

Cavity Ringdown Spectroscopy of the Hydroxy-Methyl-Peroxy Radical

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