Theoretical study of the conformers of n-butyl nitrite and their dissociation pathways leading to OH formation

Cheng, Shi‐Bo; Zhou, Can-Hua; Yin, Hongming; Han, Keli

doi:10.1016/j.cplett.2009.09.055

Cited by 4 publications

(3 citation statements)

References 42 publications

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“…As a result, conformers with a trans -CONO dihedral present a NO stretch of around 1640 cm –1 , while the cis NO stretch occurs approximately 40 cm –1 to the red (see Figures –). Previous calculations have suggested that the trans – gauche and cis – trans structures are the lowest-energy conformers for n -butyl and isobutyl nitrite and that several low-lying rotational conformers also exist. , The asymmetric appearance of the trans NO stretching transitions in the RAIRS spectra of these three molecules indicates that there are likely multiple versions of structures with a generally trans -CONO dihedral in our thin films. The cis conformer region measured for n -butyl nitrite also clearly shows a second vibrational transition, suggesting that more than one of this type of cis conformer is present.…”

Section: Resultsmentioning

confidence: 76%

“…Several groups have also examined the occurrence of rotational conformers in these compounds using both experimental and computational methods. ,,,− Microwave spectroscopy experiments have demonstrated three conformers for vapor-phase ethyl nitrite, while matrix isolation experiments showed a similar number for isopropyl nitrite, and up to eight conformers were observed for n -butyl nitrite . Generally speaking, however, primary and secondary alkyl nitrites exist as a mixture of cis and trans conformers, where these designations refer to the orientation around the CONO dihedral angle.…”

Section: Introductionmentioning

confidence: 99%

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Cold-Surface Photochemistry of Primary and Tertiary Alkyl Nitrites

2012

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Reflection-absorption infrared spectroscopy (RAIRS) is used to explore the photochemistry of primary and tertiary alkyl nitrites deposited on a gold surface. The primary alkyl nitrites examined for this study were n-butyl, isobutyl, and isopentyl nitrite. These compounds showed qualitatively similar spectra to those observed in previous condensed-phase measurements. The photolysis of the primary nitrites involved the initial formation of an alkoxy radical and NO, followed by production of nitroxyl (HNO) and an aldehydic species. In addition, the formation of nitrous oxide, identified from its distinctive transition near 2230 cm(-1), was observed to form from the self-reaction of nitroxyl. The reaction rates for cis and trans conformer decay, as tracked through their intense N═O stretching modes, were found to be significantly different, potentially due to a structural bias that favors HNO formation for the initial trans conformer photoproducts over recombination. Tert-butyl nitrite demonstrates only the trans conformer in the RAIRS spectra prior to photolysis; however, recombination of the initial NO and RO(•) photoproducts was observed to produce the cis conformer in the photolyzed samples. The primary photoproducts from tert-butyl nitrite can also react to form acetone and nitrosomethane, but the absence of HNO prohibits the formation of N(2)O that was observed for the primary alkyl nitrites. Additionally, the RAIRS spectrum of isobutyl nitrite co-deposited with water was measured to examine the photolysis of this species on a water-ice surface. No change in the identity of the photoproducts was observed in this experiment, and minimal frequency shifting (1-3 cm(-1)) of the vibrational modes occurred. In addition to being a known atmospheric source of NO and various aldehydes, our results point to cold surface processing of alkyl nitrites as a potential environmental source of nitrous oxide.

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Section: Resultsmentioning

confidence: 76%

Section: Introductionmentioning

confidence: 99%

Cold-Surface Photochemistry of Primary and Tertiary Alkyl Nitrites

2012

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“…In addition to this source of OH in this system, a minor channel that directly produces OH has been reported , . The chemistry of alkyl nitrites is important not only in the atmosphere but also because they are convenient sources of OH radicals for kinetics and mechanistic studies.…”

Section: Introductionmentioning

confidence: 94%

Hydroxyl Radical Quantum Yields from Isopropyl Nitrite Photolysis in Air

Raff

Finlayson-Pitts

2010

Environ. Sci. Technol.

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Alkyl nitrites photolyze in air to yield alkoxy radicals and NO which, through secondary reactions, generate OH radicals. This photochemistry is important in the atmosphere and in laboratory studies where nitrites are often used as a source of OH. The overall quantum yield for hydroxyl radical formation from irradiation of isopropyl nitrite (i-C(3)H(7)ONO) between 300 and 425 nm in 1 atm air at 296 ± 2 K is reported for the first time. The OH radical was scavenged by reaction with CF(3)CF═CF(2) and the formation of CF(3)CFO and CF(2)O monitored as a function of time using Fourier transform infrared spectrometry. The quantum yield was found to be 0.54 ± 0.07 (2σ) and is independent of whether or not NO was added (up to 3 × 10(14) molecules cm(-3)) prior to photolysis to increase NO concentrations above those due to the photolysis of the nitrite. Ultraviolet-visible and infrared cross sections of i-C(3)H(7)ONO are also reported. These data on the OH quantum yields as well as the UV-visible and infrared cross sections for isopropyl nitrite are critical for quantitatively interpreting the results of laboratory studies where i-C(3)H(7)ONO is employed as an OH source as well as for assessing the role of alkyl nitrites in the chemistry of the troposphere.

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