OH-Radical Oxidation of Surface-Active <i>cis</i>-Pinonic Acid at the Air–Water Interface

Enami, Shinichi; Sakamoto, Yosuke

doi:10.1021/acs.jpca.6b01261

Cited by 73 publications

(88 citation statements)

References 92 publications

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“…We note that the H-containing nascent phenol and hydroperoxide groups are able to exchange with D 2 O prior to detection B1 ms later. [10][11][12] The finding that m/z = 152 does not shift in D 2 O solvent is clearly consistent with BzO-O 2 peroxyl radical structural isomers.…”

Section: Resultssupporting

confidence: 63%

“…Also note that BzO signals do not decay as single exponentials but bottom out at large pulse energies (i.e., at large OH doses). [10][11][12]40 The rate coefficients of ( OH + BzO) via (R 1AB + R 1AD ) and ( OH + OH) via R 9 (Scheme 1) in bulk water are within a factor of two and correspond to diffusionally controlled reactions: k 1AB + k 1AD = 2.5 Â 10 9 M À1 s À1 , k 9 = 5.5 Â 10 9 M À1 s À1 . 3,41,42 Since they are also expected to be fast and commensurate at the air-water interface, the above observations imply that: (1) OH recombination into relatively inert H 2 O 2 (via R9, Scheme 1) is competitive and more extensive than its reaction with BzO in the more dilute 0.…”

Section: Resultsmentioning

confidence: 99%

“…9 It has been recently realized that the photochemical aging of particulate organic matter is not only degradative but generates volatile organic compound (VOC) emissions and reactive species, such as hydroperoxides. [10][11][12] The identification of products and labile intermediates from the heterogeneous oxidation of organic matter in condensed phases has thus emerged as a major issue in the atmospheric chemistry of polluted urban air. 6,[13][14][15] Here we address this issue and report direct, online massspecific identification of the products of the oxidation of BzO(aq) by OH(g) pulses on the surface of aqueous microjets (see Methods and Fig.…”

Section: Introductionmentioning

confidence: 99%

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Extensive H-atom abstraction from benzoate by OH-radicals at the air–water interface

Enami

Hoffmann

Colussi

2016

Phys. Chem. Chem. Phys.

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Much is known about OH-radical chemistry in the gas-phase and bulk water. Important atmospheric and biological processes, however, involve little investigated OH-radical reactions at aqueous interfaces with hydrophobic media. Here, we report the online mass-specific identification of the products and intermediates generated on the surface of aqueous (HO, DO) benzoate-h5 and -d5 microjets by ∼8 ns ˙OH(g) pulses in air at 1 atm. Isotopic labeling lets us unambiguously identify the phenylperoxyl radicals that ensue H-abstraction from the aromatic ring and establish a lower bound (>26%) to this process as it takes place in the interfacial water nanolayers probed by our experiments. The significant extent of H-abstraction vs. its negligible contribution both in the gas-phase and bulk water underscores the unique properties of the air-water interface as a reaction medium. The enhancement of H-atom abstraction in interfacial water is ascribed, in part, to the relative destabilization of a more polar transition state for OH-radical addition vs. H-abstraction due to incomplete hydration at the low water densities prevalent therein.

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Section: Resultssupporting

confidence: 63%

Section: Resultsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Extensive H-atom abstraction from benzoate by OH-radicals at the air–water interface

Enami

Hoffmann

Colussi

2016

Phys. Chem. Chem. Phys.

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“…times smaller than those at m/z 431 (and 433) from OA at [1-octanol] = [OA] = 100 mM reveals that 1-octanol is much less reactive than OA toward CIs, although both species are expected to have similar affinities for aqueous surfaces. 25,32,43,[69][70] The C 23 ethers and esters produced in each case, by having similar mass and structures (see This finding is in line with gas-phase reaction rate constants of CIs + HCOOH/CH 3 COOH, which approach collisionally controlled values: k ≥ 10 -10 cm 3 molecule -1 s -1 , 22 vs. the much smaller values for CIs + methanol/2-propanol. 48,50,68 Tobias and Ziemann have reported that rate constants of gas-phase C 13 CIs reactions with various species increase in the order: water < methanol < 2-propanol < formaldehyde < formic acid < heptanoic acid, over a 10 4…”

Section: Page 3 Of 23 Acs Paragon Plus Environmentsupporting

confidence: 65%

Reactions of Criegee Intermediates with Alcohols at Air–Aqueous Interfaces

Enami

Colussi

2017

J. Phys. Chem. A

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The fate of Criegee intermediates (CIs) from the gas-phase ozonolysis of unsaturated organic compounds in the troposphere is largely controlled by their reactions with water vapor. We recently found that against all expectations carboxylic acids compete at millimolar concentrations with water for CIs at the air-liquid interface of aqueous organic media. This outcome is consistent with both the low water concentration in the outermost interfacial layers and the enrichment of the competing acids therein. Here we show, via online electrospray mass spectrometric detection, that CIs generated in situ in the fast ozonolysis of sesquiterpenes (CH) on the surface of water:acetonitrile microjets react with n ≥ 4 linear alcohols CHOH to produce high molecular weight C ethers in one step. The OH group of 1-octanol proved to be ∼25 times less reactive than that of n-octanoic toward CIs at the same bulk molar concentration, revealing that the reactivity of hydroxylic species depends on both acidities and interfacial affinities. CI interfacial reactions with surface-active hydroxylic species, by bypassing water, represent shortcuts to molecular complexity in atmospheric aerosols.

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“…Pfrang et al, 2014;Sebastiani et al, 2015), pinonic acid (see e.g. Enami and Sakamoto, 2016), 1,2-dipalmitoyl-sn-glycero-3phosphocholine (DPPC) (see e.g. Thompson et al, 2010), or nonanoic acid (see e.g.…”

Section: Introductionmentioning

confidence: 99%

Determination of the refractive index of insoluble organic extracts from atmospheric aerosol over the visible wavelength range using optical tweezers

et al. 2018

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Abstract. Optical trapping combined with Mie spectroscopy is a new technique used to record the refractive index of insoluble organic material extracted from atmospheric aerosol samples over a wide wavelength range. The refractive index of the insoluble organic extracts was shown to follow a Cauchy equation between 460 and 700 nm for organic aerosol extracts collected from urban (London) and remote (Antarctica) locations. Cauchy coefficients for the remote sample were for the Austral summer and gave the Cauchy coefficients of A = 1.467 and B = 1000 nm2 with a real refractive index of 1.489 at a wavelength of 589 nm. Cauchy coefficients for the urban samples varied with season, with extracts collected during summer having Cauchy coefficients of A=1.465±0.005 and B=4625±1200 nm2 with a representative real refractive index of 1.478 at a wavelength of 589 nm, whilst samples extracted during autumn had larger Cauchy coefficients of A = 1.505 and B = 600 nm2 with a representative real refractive index of 1.522 at a wavelength of 589 nm. The refractive index of absorbing aerosol was also recorded. The absorption Ångström exponent was determined for woodsmoke and humic acid aerosol extract. Typical values of the Cauchy coefficient for the woodsmoke aerosol extract were A=1.541±0.03 and B=14800±2900 nm2, resulting in a real refractive index of 1.584 ± 0.007 at a wavelength of 589 nm and an absorption Ångström exponent of 8.0. The measured values of refractive index compare well with previous monochromatic or very small wavelength range measurements of refractive index. In general, the real component of the refractive index increases from remote to urban to woodsmoke. A one-dimensional radiative-transfer calculation of the top-of-the-atmosphere albedo was applied to model an atmosphere containing a 3 km thick layer of aerosol comprising pure water, pure insoluble organic aerosol, or an aerosol consisting of an aqueous core with an insoluble organic shell. The calculation demonstrated that the top-of-the-atmosphere albedo increases by 0.01 to 0.04 for pure organic particles relative to water particles of the same size and that the top-of-the-atmosphere albedo increases by 0.03 for aqueous core-shell particles as volume fraction of the shell material increases to 25 %.

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OH-Radical Oxidation of Surface-Active cis-Pinonic Acid at the Air–Water Interface

Cited by 73 publications

References 92 publications

Extensive H-atom abstraction from benzoate by OH-radicals at the air–water interface

Extensive H-atom abstraction from benzoate by OH-radicals at the air–water interface

Reactions of Criegee Intermediates with Alcohols at Air–Aqueous Interfaces

Determination of the refractive index of insoluble organic extracts from atmospheric aerosol over the visible wavelength range using optical tweezers

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