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  • 1
    Electronic Resource
    Electronic Resource
    Reactions of alkoxy radicals under atmospheric conditions: The relative importance of decomposition versus reaction with O2 (1991)
    Springer
    Journal of atmospheric chemistry 13 (1991), S. 195-210 
    Details
    ISSN: 1573-0662
    Keywords: Alkoxy radicals ; atmospheric chemistry ; isomerization ; decomposition ; reaction with O2
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Geosciences
    Notes: Abstract The reactions of alkoxy radicals determine to a large extent the products formed during the atmospheric degradations of emitted organic compounds. Experimental data concerning the decompositions, 1,5-H shift isomerizations and reactions with O2 of several classes of alkoxy radicals are inconsistent with literature estimations of their absolute or relative rate constants. An alternative, although empirical, method for assessing the relative importance under atmospheric conditions of the reactions of alkoxy radicals with O2 versus decomposition was derived. This estimation method utilizes the differences in the heats of reaction, Δ(ΔH)=(ΔHdecomposition−ΔHO 2 reaction), between these two reactions pathways. For Δ(ΔH)≲[22−0.5(ΔHO 2 reaction)], alkoxy radical decomposition dominates over the reaction with O2 at room temperature and atmospheric pressure of air, while for Δ(ΔH)≳[25-0.5(ΔHO 2 reaction)], the O2 reaction dominates over decomposition (where the units of ΔH are in kcal mol−1). The utility and shortcomings of this approach are discussed. It is concluded that further studies concerning the reactions of alkoxy radicals are needed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00115973
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  • 2
    Electronic Resource
    Electronic Resource
    Effects of ring strain on gas-phase rate constants. 2. OH radical reactions with cycloalkenes (1983)
    New York, NY : Wiley-Blackwell
    International Journal of Chemical Kinetics 15 (1983), S. 1161-1177 
    Details
    ISSN: 0538-8066
    Keywords: Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Relative rate constants for the gas-phase reactions of OH radicals with a series of cycloalkenes have been determined at 298 ± 2 K using methyl nitrite photolysis in air as a source of OH radicals. Using a rate constant for the reaction of OH radicals with isoprene of 9.60 × 10-11 cm3 molecule-1 s-1, the rate constants obtained were (X 1011 cm3 molecule-1 s-1): cyclopentene 6.39 ± 0.23, cyclohexene 6.43 ± 0.17, cycloheptene 7.08 ± 0.22, 1,3-cyclohexadiene 15.6 ± 0.5, 1,4 cyclohexadiene 9.48 ± 0.39, bicyclo[2.2.1]-2-heptene 4.68 ± 0.39, bicyclo[2.2.1] 2,5 heptadiene 11.4 ± 1.0, and bicyclo[2.2.2] 2 octene 3.88 ± 0.19. These data show that the rate constants for the nonconjugated cycloalkenes studied depend on the number of double bonds and the degree of substitution per double bond, and indicate that there are no obvious effects of ring strain energy on these OH radical addition rate constants. A predictive technique for the estimation of OH radical rate constants for alkenes and cycloalkenes is presented and discussed.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/kin.550151105
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  • 3
    Electronic Resource
    Electronic Resource
    Kinetics of the reaction of oh radicals with a series of branched alkanes at 297 ± 2 K (1984)
    New York, NY : Wiley-Blackwell
    International Journal of Chemical Kinetics 16 (1984), S. 469-481 
    Details
    ISSN: 0538-8066
    Keywords: Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Relative rate constants for the reaction of OH radicals with a series of branched alkanes have been determined at 297 ± 2 K, using methyl nitrite photolysis in air as a source of OH radicals. Using a rate constant for the reaction of OH radicals with n-butane of 2.58 × 10-12 cm3/molecule · s, the rate constants obtained are (× 1012 cm3/molecule · s): isobutane, 2.29 ± 0.06; 2-methylbutane, 3.97 ± 0.11; 2,2-dimethylbutane, 2.66 ± 0.08; 2-methylpentane, 5.68 ± 0.24; 3-methylpentane, 5.78 ± 0.11; 2,2,3-trimethylbutane, 4.21 ± 0.08; 2,4-dimethylpentane, 5.26 ± 0.11; methylcyclohexane, 10.6 ± 0.3; 2,2,3,3-tetramethylbutane, 1.06 ± 0.08; and 2,2,4-trimethylpentane, 3.66 ± 0.16. Rate constants for 2,2-dimethylbutane, 2,4-dimethylpentane, and methylclohexane have been determined for the first time, while those for the other branched alkanes are in generally good agreement with the literature data. Primary, secondary, and tertiary group rate constants at room temperature have been derived from these and previous data for alkanes and unstrained cycloalkanes, with the secondary and tertiary group rate constants depending in a systematic manner on the identity of the neighboring groups. The use of these group rate constants, together with a previous determination of the effect of ring strain energy on the OH radical rate constants for a series of cycloalkanes, allows the a priori estimation of OH radical rate constants for alkanes and cycloalkanes at room temperature.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/kin.550160413
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  • 4
    Electronic Resource
    Electronic Resource
    Rate constants for the gas-phase reaction of OH radicals with a series of ketones at 299 ± 2 K (1982)
    New York, NY : Wiley-Blackwell
    International Journal of Chemical Kinetics 14 (1982), S. 839-847 
    Details
    ISSN: 0538-8066
    Keywords: Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Relative rate constants for the reaction of OH radicals with a series of ketones have been determined at 299 ± 2 K, using methyl nitrite photolysis in air as a source of hydroxyl radicals. Using a rate constant for the reaction of OH radicals with cyclohexane of 7.57 × 10-12 cm3 molecule-1 s-1, the rate constants obtained are (× 1012 cm3 molecule-1 s-1): 2-pentanone, 4.74 ± 0.14; 3-pentanone, 1.85 ± 0.34; 2-hexanone, 9.16 ± 0.61; 3-hexanone, 6.96 ± 0.29; 2,4-dimethyl-3-pentanone, 5.43 ± 0.41; 4-methyl-2-pentanone, 14.5 ± 0.7; and 2,6-dimethyl-4-heptanone, 27.7 ± 1.5. These rate constants indicate that while the carbonyl group decreases the reactivity of C—H bonds in the α position toward reaction with the OH radical, it enhances the reactivity in the β position.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/kin.550140804
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  • 5
    Electronic Resource
    Electronic Resource
    Formation of ring-retaining products from the OH radical-initiated reactions of benzene and toluene (1989)
    New York, NY : Wiley-Blackwell
    International Journal of Chemical Kinetics 21 (1989), S. 801-827 
    Details
    ISSN: 0538-8066
    Keywords: Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The aromatic ring-retaining products formed from the gas-phase reactions of the OH radical with benzene and toluene, in the presence of NOx, have been identified and their formation yields determined. These products, and their formation yields, are as follows: from benzene - phenol, 0.236 ± 0.044; nitrobenzene, {(0.0336 ± 0.0078) + (3.07 ± 0.92) × 10-16[NO2]}; from toluene - benzaldehyde, 0.0645 ± 0.0080; benzyl nitrate, 0.0084 ± 0.0017; o-cresol, 0.204 ± 0.027; m- + p-cresol, 0.048 ± 0.009; m-nitrotoluene, {(0.0135 ± 0.0029) + (1.90 ± 0.25) × 10-16[NO2]}, where the NO2 concentration is in molecule cm-3 units. The formation yields of o- and p-nitrotoluene from toluene were ca. 0.07 and 0.35 that of m-nitrotoluene, respectively. The observations that the nitro-aromatic yields do not extrapolate to zero as the NO2 concentration approaches zero are not consistent with current chemical mechanisms for these OH radical-initiated reactions, and suggest that under the experimental conditions employed in this study the hydroxycyclohexadienyl radicals formed from OH radical addition to the aromatic ring react with NO2 rather than with O2. However, these data concerning the nitroaromatic yields are consistent with our previous conclusions that many of the nitrated polycyclic aromatic hydrocarbons present in ambient air are formed, at least in part, in the atmosphere from OH radical reactions.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/kin.550210907
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  • 6
    Electronic Resource
    Electronic Resource
    Products of the gas-phase reaction of methyl tert-butyl ether with the OH radical in the presence of NOx (1991)
    New York, NY : Wiley-Blackwell
    International Journal of Chemical Kinetics 23 (1991), S. 1003-1015 
    Details
    ISSN: 0538-8066
    Keywords: Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The products of the reaction of the hydroxyl (OH) radical with methyl tert-butyl ether (MTBE) in NOx-air systems were identified and measured by Fourier transform infrared absorption spectroscopy and gas chromatography. The products observed, and their yields, were as follows: t-butyl formate, 76 ± 7%; formaldehyde, 37-1+6%; methyl acetate, 17 ± 2%, and acetone, 2.1 ± 0.9%, where the stated error limits represent both random (two standard deviations) and estimated systematic uncertainties. These products account for ca. 95% of the MTBE carbon reacted. Infrared absorption bands which may be due to small amounts of organic nitrate formation were observed, but organic nitrate yields could not be quantified. These data allow a chemical mechanism for the reaction of MTBE with the OH radical in the presence of NOx to be formulated.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/kin.550231105
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  • 7
    Electronic Resource
    Electronic Resource
    Rate constants for the reactions of O(3P) with selected monoterpenes (1996)
    New York, NY : Wiley-Blackwell
    International Journal of Chemical Kinetics 28 (1996), S. 1-8 
    Details
    ISSN: 0538-8066
    Keywords: Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Rate constants for the gas-phase reactions of O(3P) atom with a series of monoterpenes have been determined at ambient temperature (ca. 302-309 K) and atmospheric pressure using a relative rate technique. Using the literature rate constants for O(3P) + isobutene, cis and trans-2-butene, 3-methyl-1-butene, 2-methyl-2-butene, and 2,3-dimethyl-2-butene as the standards, the O(3P) rate constants derived for the terpenes (in units of 10-11 cm3 molecule-1s -1) are 2.8 ± 0.4 for α-pinene, 2.8 ± 0.5 for β-pinene, 3.1 ± 0.5 for Δ 3-carene, 3.5 ± 0.5 for 2-carene, 2.6 ± 0.5 for camphene, 7.6 ± 1.2 for d-limonene, 9.0 ± 1.6 for γ-terpinene, and 10.7 ± 1.6 for terpinolene. The relative rate constants in this work agreed with literature values to within ± 10% for the standard alkenes, and to within ± ca. 35% for the terpenes. © 1996 John Wiley & Sons, Inc.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/kin.1
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  • 8
    Electronic Resource
    Electronic Resource
    A smog chamber and modeling study of the gas phase NOx-air photooxidation of toluene and the cresols (1980)
    New York, NY : Wiley-Blackwell
    International Journal of Chemical Kinetics 12 (1980), S. 779-836 
    Details
    ISSN: 0538-8066
    Keywords: Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: An experimental and modeling study of irradiated toluene-NOx-air, toluene-benzaldehyde-NOx-air, and cresol-NOx-air mixtures at part-per-million concentrations has been carried out. These mixtures were irradiated at 303 ± 1 K in a 5800-liter Teflon-lined, evacuable environmental chamber, with temperature, humidity, light intensity, spectral distribution, and the concentrations of O3, NO, NO2, toluene, PAN, formaldehyde, benzaldehyde, o-cresol, m-nitrotoluene, and methyl nitrate beingmonitored as a function of time. For the toluene and toluene-benzaldehyde-NOx-air runs a variety of initial reactant concentrations were investigated. Cresol-NOx-air runs were observed to be much less reactive in terms of O3 formation and NO to NO2 conversion rates than toluene-NOx-air runs, with the relative reactivity of the cresol isomers being in the order meta » ortho 〉 para. The addition of benzaldehyde to toluene-NOx-air mixtures decreased the reactivity, in agreement with previous studies. Alternative mechanistic pathways for the NOx photooxidations of aromaticsystems in general are discussed, and the effects of varying these mechanistic alternatives on the model predictions for the toluene and o-cresol-NOx-air systems are examined. Fits of the calculations to most of the experimental concentration-time profiles could be obtained to within the experimental uncertainty for two of the mechanistic options considered. In both cases it is assumed that (1) O2 adds to the OH-toluene adduct ∼75% of the time forming, after a further addition of O2, a C7 bicyclic peroxy radical, and (2) this C7 bicyclic peroxy radical reacts with NO ∼75% of the time to ultimately form α-dicarbonyls and conjugated γ-dicarbonyls (e.g., methylglyoxal + 2-butene-1,4-dial) and ∼25% of the time to form organic nitrates. The major uncertainties in the mechanisms concern (1) the structure of the bicyclicperoxy intermediate, and (2) the γ-dicarbonyl photooxidation mechanism. Good fits to the o-cresol concentration-time profiles in the toluene-NOx runs are obtained if it is assumed that o7-cresol reacts rapidly with NO3 radicals. However, it is observed that the model underpredicts nitrotoluene yields by a factor of ∼10, but this is in any case a minor product. It is concluded that further experimental work will be required toadequately validate the assumptions incorporated in the aromatic photooxidation mechanisms presented here.
    Additional Material: 8 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/kin.550121102
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  • 9
    Electronic Resource
    Electronic Resource
    Kinetics of the gas-phase reactions of NO3 radicals with a series of aromatics at 296 ± 2 K (1984)
    New York, NY : Wiley-Blackwell
    International Journal of Chemical Kinetics 16 (1984), S. 887-898 
    Details
    ISSN: 0538-8066
    Keywords: Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Rate constants have been determined at 296 ± 2 K for the gas phase reaction of NO3 radicals with a series of aromatics using a relative rate technique. The rate constants obtained (in cm3 molecule-1 s-1 units) were: benzene, 〈2.3 × 10-17; toluene, (1.8 ± 1.0) × 10-17; o—xylene, (1.1 ± 0.5) × 10-16; m—xylene, (7.1 ± 3.4) × 10-17; p—xylene, (1.4 ± 0.6) × 10-16; 1,2,3-trimethylbenzene, (5,6 ± 2.6) × 10-16; 1,2,4-trimethylbenzene (5.4 - 2.5) × 10-16; 1,3,5-trimethylbenzene, (2.4 ± 1.1) × 10-16; phenol, (2.1 ± 0.5) × 10-12; methoxybenzene, (5.0 ± 2.8) × 10-17; o-cresol, (1.20 ± 0.34) × 10-11; m-cresol, (9.2 ± 2.4) × 10-12; p-cresol, (1.27 ± 0.36) × 10-11; and benzaldehyde, (1.13 ± 0.25) × 10-15. These kinetic data, together with, in the case of phenol, product data, suggest that these reactions proceed via H-atom abstraction from the substituent groups. The magnitude of the rate constants for the hydroxy-substituted aromatics indicates that the nighttime reaction of NO3 radicals with these aromatics can be an important loss process for both NO3 radicals and these organics, as well as being a possible source of nitric acid, a key component of acid deposition.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/kin.550160709
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  • 10
    Electronic Resource
    Electronic Resource
    Rate constants for the gas-phase reactions of OH radicals with a series of bi- and tricycloalkanes at 299 ± 2 K: Effects of ring strain (1983)
    New York, NY : Wiley-Blackwell
    International Journal of Chemical Kinetics 15 (1983), S. 37-50 
    Details
    ISSN: 0538-8066
    Keywords: Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Relative rate constants for the gas-phase reactions of OH radicals with a series of bi- and tricyclic alkanes have been determined at 299 ± 2 K, using methyl nitrite photolysis in air as a source of OH radicals. Using a rate constant for the reaction of OH radicals with cyclohexane of 7.57 × 10-12 cm3/molec·s, the rate constants obtained are (× 1012 cm3/molec·s): bicyclo[2.2.1]heptane, 5.53 ± 0.15; bicyclo[2.2.2]octane, 14.8 ± 1.0; bicyclo[3.3.0]octane, 11.1 ± 0.6; cis-bicyclo[4.3.0]nonane, 17.3 ± 1.3; trans-bicyclo[4.3.0]nonane, 17.8 ± 1.3; cis-bicyclo[4.4.0]decane, 20.1 ± 1.4; trans-bicyclo[4.4.0]decane, 20.6 ± 1.2; tricyclo[5.2.1.02,6]decane, 11.4 ± 0.4; and tricyclo[3.3.1.13,7]decane, 23.2 ± 2.1. These data show that overall ring strain energies of ≲4-5 kcal mol-1 have no significant effect on the rate constants, but that larger ring strain results in the rate constants being decreased, relative to those expected for the strain-free molecules, by ratios which increase approximately exponentially with the overall ring strain.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/kin.550150105
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