1999 Progress Report: Atmospheric Chemistry of Volatile Organic Compounds and their Atmospheric Reaction Products

EPA Grant Number: R825252
Title: Atmospheric Chemistry of Volatile Organic Compounds and their Atmospheric Reaction Products
Investigators: Atkinson, Roger , Arey, Janet , Tuazon, Ernesto C.
Institution: University of California - Riverside
EPA Project Officer: Shapiro, Paul
Project Period: November 1, 1996 through October 31, 1999 (Extended to October 31, 2000)
Project Period Covered by this Report: November 1, 1998 through October 31, 1999
Project Amount: $387,254
RFA: Air Quality (1996) RFA Text |  Recipients Lists
Research Category: Air Quality and Air Toxics , Air

Objective:

In this 3-year experimental program, we are using the array of analytical methods currently available at the Air Pollution Research Center (APRC) at the University of California, Riverside, to investigate the atmospherically important reactions of selected volatile organic compounds (VOCs) and of their reaction products. In particular, we are using our PE SCIEX API III MS/MS direct air sampling, atmospheric pressure ionization tandem mass spectrometer (API-MS/MS) in conjunction with in situ Fourier transform infrared (FT-IR) spectroscopy, gas chromatography with flame ionization detection (GC-FID), gas chromatography with FTIR detection (GC-FTIR), combined gas chromatography-mass spectrometry (GC-MS), and product derivatization with GC-FID, GC-MS, and GC-FTIR analyses to identify and quantify VOC reaction products. The studies being carried out are a continuation and extension of previous research at APRC. Specifically, during this 3-year experimental program we proposed to:

? Quantitatively extend our previous API-MS/MS studies of the formation of hydroxycarbonyls from the OH radical-initiated reactions of alkanes and alkenes. A derivatization method currently being tested and used in our laboratory, involving the conversion of alcohol -OH groups to the trimethylsilyl, -OSi(CH3)3, group, will be used to identify and quantify the -hydroxycarbonyls formed in the OH radical-initiated reactions of isoprene and n-butane through n-octane, and the dihydroxycarbonyls formed from the OH radical-initiated reactions of 1-butene through 1-octene. This work will complete, on a quantitative level, our recent semi-quantitative API-MS/MS studies of these reactions (Kwok, et al., 1996a,b). In addition, by using the gas-phase reactions of O3 with alkenes to generate OH radicals, the OH radical reactions with alkenes (and other VOCs) can be studied.

? Study the products of the OH radical-initiated reactions of a series of branched alkanes, including 2,2,4-trimethylpentane and 2,2,4-trimethylpentane-d18. These studies will involve analyses of the reaction products by gas chromatography (GC-FID, GC-MS, and GC-FTIR) and by API-MS/MS, together with derivatization of hydroxycarbonyls and any other hydroxy-compounds with analysis of their trimethylsilyl-derivatives by GC-FID, GC-FTIR, and GC-MS. Deuterated branched alkanes will be obtained and used whenever commercially available for the API-MS/MS analyses to aid in the interpretation of the MS and MS/MS data. These studies of the n-alkanes and branched alkanes will lead to quantitative information concerning the relative importance of isomerization, decomposition, and reaction with O2 for the various alkoxy radicals formed in these reaction systems. These data will be used to develop methods for the calculation of the rate constants for alkoxy radical reaction pathways in the troposphere.

? Study the products of the gas-phase reactions of selected alkenes with NO3 radicals and O3, using API-MS/MS, in situ FT-IR absorption spectroscopy, and gas chromatography (GC-FID, GC-MS, and GC-FTIR) with (for the NO3 radical reactions) and without derivatization.

? Investigate the atmospheric chemistry of hydroxycarbonyls formed from the alkanes and of dihydroxycarbonyls formed from alkenes. Because only a few hydroxycarbonyls are commercially available and many of these are not amenable to gas chromatography without derivatization, we will study the reactions of these compounds using API-MS/MS, in situ FT-IR absorption spectroscopy, and gas chromatography (GC-FID, GC-MS, and GC-FTIR) with and without derivatization. It should be noted that the reaction products of the hydroxycarbonyls are expected to include dicarbonyl and carbonyl compounds that can be analyzed by gas chromatography without derivatization. We recently have shown that 5-hydroxy-2-pentanone, commercially available but not amenable to gas chromatography without derivatization, can readily be monitored (though not necessarily quantitatively) by API-MS (Kwok, et al., 1996a). We will use in situ FT-IR absorption spectroscopy and gas chromatography after derivatization to monitor the hydroxycarbonyls, with identification and quantification of the products by GC-FID, GC-MS, and GC-FTIR (with and without derivatization), in situ FT-IR absorption spectroscopy, and API-MS/MS. These experiments will include rate constant measurements as well as product studies of a series of commercially available and/or synthesized ?-, a-, ?- and c-hydroxycarbonyls.

? Investigate the products formed from selected carbonyl compounds, using gas chromatography (GC-FID, GC-MS, and GC-FTIR), in situ FT-IR absorption spectroscopy, and API-MS/MS. The carbonyl compounds chosen for study will include 4-methyl-2-pentanone (and 4-methyl-2-pentanone-1,1,1,3,3-d5 for the API-MS/MS studies) and 2,6-dimethyl-4-heptanone for which we have previously used gas chromatography to analyze for selected products (Atkinson and Aschmann, 1995).

? Continue our investigation of the products of the gas-phase reactions of the OH radical with aromatic hydrocarbons in the presence and absence of NOx using API- MS/MS and gas chromatographic (GC-FID, GC-MS, and GC-FTIR) analyses. In situ FT-IR absorption spectroscopy in the 5,800 liter evacuable chamber also will be used for analyses whenever it is believed to be advantageous. These studies will extend our API-MS/MS investigation of the products of the reactions of the OH radical with o-, m-, and p-xylene (and the partially and fully deuterated xylenes) (Kwok, et al., 1997) to other aromatic hydrocarbons.

? Investigate the atmospheric chemistry of the unsaturated dicarbonyls observed from the OH radical-initiated reactions of aromatic hydrocarbons. This may involve the in situ formation of these compounds from the xylene reactions (Kwok, et al., 1997), with the time-concentration profiles of these products as observed by API-MS (and possibly in situ FT-IR absorption spectroscopy) providing data concerning their rate constants for reaction with OH radicals and knowledge as to their reaction products.

? Investigate the products of the gas-phase reactions of OH radicals and NO3 radicals with phenol and o-cresol, using primarily API-MS/MS. Phenolic compounds have been reported to be formed in significant yield from the reactions of the OH radical with benzene and toluene, respectively, in the presence of NOx, and the products of their tropospheric reactions are presently only poorly understood.

The experimental data obtained in this program will provide critically important information concerning the products formed, and their yields, from the gas-phase reactions of selected VOCs and their first-generation reaction products with OH radicals, NO3 radicals, and O3 under atmospheric conditions.

Progress Summary:

During the third year of this project, we have investigated selected aspects of the atmospheric chemistry of alkanes, oxygenated VOCs, and aromatic hydrocarbons, as briefly discussed below.

Alkanes. As noted in the Objectives above, one of our goals is to better understand the reactions of alkoxy radicals in the troposphere. As an extension of our earlier work on alkoxy radicals formed from the OH radical-initiated reactions of n-alkanes, we have completed an investigation of the products of the reactions of the OH radical with 2,2,4-trimethylpentane and its deuterated analog in the presence of NO, using gas chromatography and in situ API-MS to identify and quantify the reaction products. We have observed the formation of hydroxynitrates of molecular weights 135, 177, and 191, hydroxycarbonyls of molecular weights 116, 130, and 144, other products of molecular weights 128 and 142, and have quantified the formation yields of acetone and 2-methylpropanal from the 2,2,4-trimethylpentane reaction (and determined upper limits to the formation yields of 2,2-dimethylpropanal and 4,4-dimethyl-2-pentanone). A manuscript describing this study currently is being prepared for submission to Environmental Science & Technology.

Oxygenated VOCs. We have measured rate constants for the gas-phase reactions of OH radicals and NO3 radicals with propanal, butanal, pentanal, and hexanal at room temperature, and showed (in agreement with an earlier literature study) that the rate constants for the NO3 radical reactions increase markedly with increasing carbon number, in contrast to the OH radical reactions. A manuscript describing this work currently is in press in the International Journal of Chemical Kinetics.

We have observed that a number of hydroxyketones (but not -hydroxyketones) can be analyzed by gas chromatography without derivatization. Accordingly, we have investigated the formation of ?-hydroxycarbonyls from the reactions of the OH radical with trans-2-butene, trans-3-hexene, 1-butene, and ?-pinene in the presence and absence of NOx (forming OH radicals in the absence of NOx from the O3 reactions with the alkene being studied). The data obtained in the presence of NOx show that the intermediate ?-hydroxyalkoxy radicals decompose rather than react with O2 to form the ?-hydroxycarbonyls, and rate constant ratios kdecomposition/kO2 for the intermediate ?-hydroxyalkoxy radicals were derived, where kdecomposition and kO2 are the rate constants for the decomposition and reaction with O2 of the ?-hydroxyalkoxy radicals, respectively. In the absence of NOx, peroxy radical + peroxy radical reactions become important and we observed the formation of ?-hydroxycarbonyls and 1,2-diols under these conditions. A manuscript describing this research has been submitted for publication to Environmental Science & Technology.

We also have measured rate constants for the reactions of OH radicals, NO3 radicals, and O3 with the hydroxyketones 1-hydroxy-2-butanone, 3-hydroxy-2-butanone, 1-hydroxy-3-butanone, 1-hydroxy-2-methyl-3-butanone, 3-hydroxy-3-methyl-2-butanone, and 4-hydroxy-3-hexanone at room temperature, and a manuscript describing this study has been submitted for publication to the Journal of Physical Chemistry A.

Aromatic Hydrocarbons. We have investigated the formation of 2,3-butanedione (biacetyl) and 3-hexene-2,5-dione (CH3C(O)CH=CHC(O)CH3) (and selected other products) from the reactions of the OH radical with p-xylene and 1,2,3- and 1,2,4-trimethylbenzene as a function of the NO2 concentration. Formation yields have been measured for the formation of p-tolualdehyde, 2,5-dimethylphenol, and 3-hexene-2,5-dione from p-xylene, 2,3-butanedione from 1,2,3- trimethylbenzene, and 2,3-butanedione and 3-hexene-2,5-dione from 1,2,4-trimethylbenzene. While the formation yields of p-tolualdehyde and 2,5-dimethylphenol from p-xylene showed no evidence for a dependence on the NO2 concentration (in agreement with an earlier study [1991] from this laboratory), the formation yields of ring-opened products from p-xylene and 1,2,3- and 1,2,4-trimethylbenzene decreased with increasing NO2 concentration. Furthermore, our formation yields for 3-hexene-2,5-dione are similar to those reported in previous studies for glyoxal (the expected co-product). A manuscript describing this work is being prepared for submission to a peer-reviewed journal.

Future Activities:

We have a 1-year no-cost extension to this program, which will enable us to complete studies of the atmospheric reactions of selected diols (to form, at least in part, hydroxycarbonyls) and aromatic compounds.

References:

Atkinson R, Aschmann SM. Products of the gas-phase OH radical-initiated reactions of 4-methyl-2-pentanone and 2,6-dimethyl-4-heptanone. Int J Chem Kinet 1995;27:261–275.

Kwok ESC, Arey J, Atkinson R. Alkoxy radical isomerization in the OH radical-initiated reactions of C4-C8 n-alkanes. J Phys Chem 1996a;100:214–219.

Kwok ESC, Atkinson R, Arey J. Isomerization of β-hydroxyalkoxy radicals formed from the OH radical-initiated reactions of C4-C8 1-alkenes. Environ Sci Technol 1996b;30:1048–1052.

Kwok ESC, Aschmann SM, Atkinson R, Arey J. Products of the gas-phase reactions of o-, m- and p-xylene with the OH radical in the presence and absence of NOx. J Chem Soc Faraday Trans 1997;93:2847–2854.


Journal Articles on this Report : 12 Displayed | Download in RIS Format

Other project views: All 27 publications 13 publications in selected types All 13 journal articles
Type Citation Project Document Sources
Journal Article Aschmann SM, Chew AA, Arey J, Atkinson R. Products of the gas-phase reaction of OH radicals with cyclohexane: Reactions of the cyclohexoxy radical. Journal of Physical Chemistry A 1997;101(43):8042-8048. R825252 (1998)
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  • Abstract: American Chemical Society Publications Abstract
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  • Journal Article Aschmann SM, Atkinson R. Products of the gas-phase reactions of the OH radical with n-butyl methyl ether and 2-isopropoxyethanol: Reactions of ROC(O)< radicals. International Journal of Chemical Kinetics 1999;31(7):501-513. R825252 (1998)
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  • Journal Article Aschmann SM, Arey J, Atkinson R. Atmospheric chemistry of selected hydroxycarbonyls. Journal of Physical Chemistry A Molecules 2000;104(17):3998-4003. R825252 (1998)
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  • Full-text: American Chemical Society Full Text
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  • Abstract: American Chemical Society Abstract
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  • Journal Article Aschmann SM, Arey J, Atkinson R. Formation of β-hydroxycarbonyls from the OH radical-initiated reactions of selected alkenes. Environmental Science & Technology 2000;34(9):1702-1706. R825252 (1998)
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  • Journal Article Aschmann Sm, Arey J, Atkinson R. Products and mechanism of the reaction of OH radicals with 2,2,4-trimethylpentane in the presence of NO. Environmental Science and Technology 2002;36(4):625-632. R825252 (1998)
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  • Journal Article Bethel HL, Atkinson R, Arey J. Products of the gas-phase reactions of OH radicals with p-xylene and 1,2,3- and 1,2,4-trimethylbenzene: effect of NO2 concentration. Journal of Physical Chemistry A 2000;104(39):8922-8929. R825252 (1998)
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    R826371C007 (Final)
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  • Journal Article Bethel HL, Atkinson R, Arey J. Kinetics and products of the reactions of selected diols with the OH radical. International Journal of Chemical Kinetics 2001;33(5):310-316. R825252 (1998)
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    R826371C007 (Final)
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  • Journal Article Chew AA, Atkinson, Aschmann SM. Kinetics of the gas-phase reactions of NO3 radicals with a series of alcohols, glycol ethers, ethers, and chloroalkenes. Journal of the Chemical Society Faraday Transactions 1998;94(8):1083-1089. R825252 (1998)
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  • Journal Article Harry C, Atkinson R, Arey J. Rate constants for the reactions of OH radicals and Cl atoms with di-n-propyl ether and di-n-butyl ether and their deuterated analogs. International Journal of Chemical Kinetics 1999;31(6):425-431. R825252 (1998)
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  • Journal Article Papagni C, Arey J, Atkinson R. Rate constants for the gas-phase reactions of a series of C3—C6 aldehydes with OH and NO3 radicals. International Journal of Chemical Kinetics 2000;32(2):79-84. R825252 (1998)
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  • Journal Article Tuazon EC, Aschmann SM, Atkinson R, Carter WPL. The reactions of selected acetates with the OH radical in the presence of NO: Novel rearrangement of alkoxy radicals of structure RC(O)OCH(O)R. Journal of Physical Chemistry A 1998;102(13):2316-2321. R825252 (1998)
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  • Journal Article Tuazon EC, Alvarado A, Aschmann SM, Atkinson R, Arey J. Products of the gas-phase reactions of 1,3-butadiene with OH and NO3 radicals. Environmental Science and Technology 1999;33(20):3586-3595. R825252 (1998)
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  • Supplemental Keywords:

    hydroxyl radical, nitrate radical, ozone, reaction products., RFA, Scientific Discipline, Air, air toxics, Environmental Chemistry, tropospheric ozone, Atmospheric Sciences, exposure and effects, spectroscopic studies, VOCs, air quality data, air sampling, gas chromatography, chemical kinetics, atmospheric chemical cycles, alkenes, atmospheric monitoring, infrared spectroscopy, atmospheric reaction products, hydroxycarbonyls

    Progress and Final Reports:

    Original Abstract
  • 1997
  • 1998 Progress Report
  • Final Report