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  • Chemistry  (19)
  • Physical Chemistry  (19)
  • Alkoxy radicals  (1)
  • 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
    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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  • 3
    Electronic Resource
    Electronic Resource
    Kinetics of the gas-phase reactions of OH radicals with alkyl nitrates at 299 ± 2 K (1982)
    New York, NY : Wiley-Blackwell
    International Journal of Chemical Kinetics 14 (1982), S. 919-926 
    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 alkyl nitrates 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): 2-propyl nitrate, 0.18 ± 0.05; 1-butyl nitrate, 1.42 ± 0.11; 2-butyl nitrate, 0.69 ± 0.10; 2-pentyl nitrate, 1.87 ± 0.12; 3-pentyl nitrate, 1.13 ± 0.20; 2-hexyl nitrate, 3.19 ± 0.16; 3-hexyl nitrate, 2.72 ± 0.22; 3-heptyl nitrate, 3.72 ± 0.43; and 3-octyl nitrate, 3.91 ± 0.80. These rate constants, which are the first reported for the alkyl nitrates, are significantly lower than those for the parent alkanes, and a formula, based on the numbers of the various types of C—H bonds in the alkyl nitrates, is derived for rate constant estimation purposes.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/kin.550140810
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  • 4
    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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  • 5
    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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  • 6
    Electronic Resource
    Electronic Resource
    The gas-phase reaction of hydrazine and ozone: A nonphotolytic source of OH radicals for measurement of relative OH radical rate constants (1983)
    New York, NY : Wiley-Blackwell
    International Journal of Chemical Kinetics 15 (1983), S. 619-629 
    Details
    ISSN: 0538-8066
    Keywords: Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The homogeneous gas-phase reaction of N2H4 with O3 in air atmospheric pressure has been used to generate OH radicals in the dark, allowing the determination of relative OH radical rate constants for compounds which photolyze rapidly. This technique was first validated by determining the OH radical rate constant ratios for n-butane/cyclohexane and methanol/dimethyl ether, both of which are in excellent agreement with the literature values. The rate constant for the reaction of OH radicals with methyl nitrite at 300 ± 3 K was then determined relative to those for the reaction of OH radicals with n-hexane and dimethyl ether. The resulting rate constant of 1.8 × 10-13 cm3/molecule·s is about seven times lower than those of previous measurements which employed a different nonphotolytic relative rate method.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/kin.550150704
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  • 7
    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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  • 8
    Electronic Resource
    Electronic Resource
    Computer modeling of smog chamber data: Progress in validation of a detailed mechanism for the photooxidation of propene and n-butane in photochemical smog (1979)
    New York, NY : Wiley-Blackwell
    International Journal of Chemical Kinetics 11 (1979), S. 45-101 
    Details
    ISSN: 0538-8066
    Keywords: Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A detailed mechanism is presented for reactions occurring during irradiation of part-per-million concentrations of propene and/or n-butane and oxides of nitrogen in air. Data from an extensive series of well-characterized smog chamber experiments carried out in our 5800-liter evacuable chamber-solar simulator facility designed for providing data suitable for quantitative model validation were used to elucidate several unknown or uncertain kinetic parameters and details of the reaction mechanism.The mechanism was then tested against the data base from the smog chamber runs. In general, most calculated concentration-time profiles agreed with experiments to within the experimental uncertainties. Fits were usually attained to within ∼±20% or better for ozone, NO, propene, and n-butane, to within ∼±30% or better for NO2, PAN, methyl ethyl ketone, 2-butyl nitrate, butyraldehyde, and (in runs not containing propene) methyl nitrate, to within ⋐±50% or better for the minor products 1-butyl nitrate and propene oxide, and to within a factor of 2 for methyl nitrate in propene-containing runs. Propionaldehyde was consistently underpredicted in all runs; it is probably a chamber contaminant. For formaldehyde and acetaldehyde, the major products in both systems, fits to within ⋐±20% were often obtained, yet for a number of experiments, significantly greater discrepancies were observed, probably as a result of experimental and/or analytical problems.The good fits to experimental data were attained only after adjusting several rate constants or rate constant ratios related to uncertainties concerning chamber effects or the chemical mechanism. The largest uncertainty concerns the necessity to include in the mechanism a significant rate of radical input from unknown sources in the smog chamber. Other areas where fundamental kinetic and mechanistic data are most needed before a predictive, detailed propene + n-butane-NOx-air smog model can be completely validated concern other chamber effects, the O3 + propene mechanism, decomposition rates of substituted alkoxy radicals, primary quantum yields for radical production as a function of wavelength for aldehyde and ketone photolyses, and the mechanisms and rates of reactions of peroxy radicals with NO and NO2.
    Additional Material: 12 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/kin.550110105
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  • 9
    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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  • 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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