Rate constants for the gas-phase reactions of the OH radical with a series of monoterpenes at 294 ± 1 K

Using a relative rate technique, rate constants for the gas-phase reactions of the OH radical with a series of monoterpenes have been determined in one atmosphere of air at 294 ± 1 K. Relative to a rate constant for the reaction of OH radicals with 2,3-dimethyl-2-butene of 1.12 × 10^?10 cm³ molecule^?1 sec^?1, the rate constants obtained were (in units of 10^?11 cm³ molecule^?1 sec^?1): α-Pinene, 5.45 ± 0.32; β-pinene, 7.95 ± 0.52; Δ³-carene, 8.70 ± 0.43; d-limonene, 16.9 ± 0.5; α-terpinene, 36.0 ± 4.0; γ-terpinene, 17.6 ± 1.8; α-phellandrene, 31.0 ± 7.1; myrcene, 21.3 ± 1.6; and ocimene (acis-, trans-mixture), 25.0 ± 1.9. These are the first quantitative kinetic data reported for many of these monoterpenes. The rate constants obtained are compared with the available literature data and with a priori estimates based on the number and configuration of substituents around the double bond(s). The tropospheric lifetimes of these monoterpenes with OH radicals, NO₃ radicals and O₃ are estimated and compared. Atmospheric lifetimes with respect to reaction with the OH radical are calculated to range from ～0.75 hr for α-terpinene to ～5 hr for α-pinene.     

Rate constants for the gas-phase reactions of O3 with a series of alkenes at 296 ± 2 K

The kinetics of the gas-phase reactions of O₃ with a series of alkenes have been investigated at atmospheric pressure (ca. 740 torr) of air and 296 ± 2 K, using a relative rate method in the presence of sufficient n-octane to scavenge any OH radicals generated in these reactions. Relative to k(O₃ + propene) = 1.00, the rate constants obtained were: 1-butene, 0.975 ± 0.030; 2-methylpropene, 1.14 ± 0.04; 2-methyl-1,3-butadiene (isoprene), 1.21 ± 0.02; 1,4-cyclohexadiene, 4.75 ± 0.23; cyclohexene, 7.38 ± 0.48; cis-2-butene, 12.8 ± 0.8; trans-2-butene, 21.5 ± 1.5; 2-methyl-2-butene, 42.1 ± 2.8; cyclopentene, 64.9 ± 4.3; and 2,3-dimethyl-2-butene, 123 ± 11. These relative rate constants have been placed on an absolute basis using a rate constant for the reaction of O₃ with propene of 1.01 × 10^?17 cm³ molecule^?1 s^?1 at 296 K derived from an analysis of the available literature data. The resulting rate constants then lead to a self-consistent set of room temperature data for the reactions of O₃ with these alkenes. © John Wiley & Sons, Inc.     

Rate constants for the gas-phase reactions of O3 with a series of Terpenes and OH radical formation from the O3 reactions with Sesquiterpenes at 296 ± 2 K

Rate constants for the gas-phase reactions of O₃ with the sesquiterpenes α-cedrene, α-copaene, β-caryophyllene, α-humulene, and longifolene, and with the monoterpenes limonene, terpinolene, α-phellandrene, and α-terpinene, have been measured using a relative rate technique at 296 ± 2 K and atmospheric pressure of air. The rate constants obtained (in units of 10^?17 cm³ molecule^?1 s^?1) are: limonene, 20.1 ± 5.1; terpinolene, 188 ± 67; α-phellandrene, 298 ± 105; α-terpinene, 2110 ± 770; α-cedrene, 2.78 ± 0.71; α-copaene, 15.8 ± 5.6; β-caryophyllene, 1160 ± 430; α-humulene, 1170 ± 450; and longifolene, <0.07, where the indicated errors include the estimated overall uncertainties in the rate constants for the reference organics. Hydroxyl radical formation yields were also determined for the O₃ reactions with the sesquiterpenes, of 0.67 for α-cedrene, 0.35 for α-copaene, 0.06 for β-caryophyllene, and 0.22 for α-humulene, all with estimated overall uncertainties of a factor of ca. 1.5. The tropospheric lifetimes of the sesquiterpenes due to reaction with O₃ are calculated. © 1994 John Wiley & Sons, Inc.     

Rate constants for the gas-phase reactions of alkanes with Cl atoms at 296 ± 2 K

Rate constants for the gas-phase reactions of the Cl atom with a series of alkanes have been determined at 296 ± 2 K using a relative rate method. Using a rate constant for the Cl atom reaction with n-butane of 1.94 × 10^?10 cm³ molecule^?1 s^?1, the rate constants obtained (in units of 10^?11 cm³ molecule^?1 s^?1) were: 2-methylpentane, 25.0 ± 0.8; 3-methylpentane, 24.8 ± 0.6; cyclohexane, 30.8 ± 1.2; cyclohexane-d₁₂, 25.6 ± 0.8; 2,4-dimethylpentane, 25.6 ± 1.2; 2,2,3-trimethylbutane, 17.9 ± 0.7; methylcyclohexane, 34.7 ± 1.2; n-octane, 40.5 ± 1.2; 2,2,4-trimethylpentane, 23.1 ± 0.8; 2,2,3,3-tetramethylbutane, 15.6 ± 0.9; n-nonane, 42.9 ± 1.2; n-decane, 48.7 ± 1.8; and cis-bicyclo[4.4.0]decane, 43.1 ± 0.8, where the indicated errors are two least-squares standard deviations and do not include the uncertainties in the n-butane rate constant. These data have been combined with rate constants obtained previously for ten C₂? C₇ alkanes and this entire data set has been used to develop an estimation method allowing the room temperature rate constants for the reactions of the Cl atom with alkanes to be calculated. © 1995 John Wiley & Sons, Inc.     

Rate constants for the gas-phase reactions of O3 with a series of monoterpenes and related compounds at 296 ± 2 K

Rate constants for the gas-phase reactions of O₃ with a series of monoterpenes and related compounds have been determined at 296 ± 2 K and 740 torr total pressure of air or O₂ using a combination of absolute and relative rate techniques. Good agreement between the absolute and relative rate data was observed, and the rate constants obtained (in units of 10^?17 cm³ molecule^?1 s^?1) were: α-pinene, 8.7; β-pinene, 1.5; Δ³-carene, 3.8; 2-carene, 24; sabinene, 8.8; d-limonene, 21; γ-terpinene, 14; terpinolene, 140; α-phellandrene, 190; α-terpinene, 870; myrcene, 49; trans-ocimene, 56; p-cymene, <0.005; and 1,8-cineole, <0.015. While these rate constants for α- and β-pinene and sabinene are in good agreement with recent absolute and relative rate determinations, those for the other monoterpenes are generally lower than the literature data by factors of ca. 2–10. The measured rate constants for the monoterpenes are reasonably consistent with predictions based upon the number and positions of the substituent groups around the 〉C?C〈 bond(s).     

Rate constants for the gas-phase reaction of OH radicals with a series of ketones at 299 ± 2 K

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.     

Rate constants for the gas-phase reactions of O3 with a series of carbonyls at 296 K

Rate constants for the gas-phase reactions of O₃ with the carbonyls acrolein, crotonaldehyde, methacrolein, methylvinylketone, 3-penten-2-one, 2-cyclohexen-1-one, acetaldehyde, and methylglyoxal have been determined at 296 ± 2 K. The rate constants ranged from <6 × 10^?21 cm³ molecule^?1 s^?1 for acetaldehyde to 2.13 × 10^?17 cm³ molecule^?1 s^?1 for 3-penten-2-one. The substituent effects of ? CHO and CH₃CO? groups on the rate constants are assessed and discussed, as are implications for the atmospheric chemistry of the natural hydrocarbon isoprene.     

Rate constants for the gas‐phase reactions of O3 with a series of cycloalkenes at 296 ± 2 K

Using a relative rate method, rate constants for the gas phase reactions of O₃ with 1‐ and 3‐methylcyclopentene, 1‐, 3‐, and 4‐methylcyclohexene, 1‐methylcycloheptene, cis‐cyclooctene, 1‐ and 3‐methylcyclooctene, 1,3‐ and 1,5‐cyclooctadiene, and 1,3,5,7‐cyclooctatetraene have been measured at 296 ± 2 K and atmospheric pressure of air. The rate constants obtained (in units of 10^?18 cm³ molecule^?1 s^?1) are 1‐methylcyclopentene, 832 ± 24; 3‐methylcyclopentene, 334 ± 12; 1‐methylcyclohexene, 146 ± 10; 3‐methylcyclohexene, 55.3 ± 2.6; 4‐methylcyclohexene, 73.1 ± 3.6; 1‐methylcycloheptene, 930 ± 24; cis‐cyclooctene, 386 ± 23; 1‐methylcyclooctene, 1420 ± 100; 3‐methylcyclooctene, 139 ± 9; cis,cis‐1,3‐cyclooctadiene, 20.0 ± 1.4; 1,5‐cyclooctadiene, 152 ± 10; and 1,3,5,7‐cyclooctatetraene, 2.60 ± 0.19, where the indicated errors are two least‐squares standard deviations and do not include the uncertainties in the rate constants for the reference alkenes (propene, 1‐butene, cis‐2‐butene, trans‐2‐butene, 2‐methyl‐2‐butene, and terpinolene). These rate data are compared with the few available literature data, and the effects of methyl substitution discussed. © 2005 Wiley Periodicals, Inc. Int J Chem Kinet 37: 183–190, 2005     

Rate constants for the gas-phase reactions of Cl atoms with a series of hydrofluorocarbons and hydrochlorofluorocarbons at 298 ± 2 K

A relative rate method has been used to determine rate constants for the gas-phase reactions of a series of hydrofluorocarbons (HFCs) and hydrochlorofluorocarbons (HCFCs) at 298 ± 2 K and atmospheric pressure of air. Based on a rate constant for the reaction of the Cl atom with CH₄ of (1.0 ± 0.2) ? 10^?13 cm³ molecule^?1 s^?1 at 298 K, the following Cl atom reaction rate constants (in units of 10^?15 cm³ molecule^?1 s^?1) were obtained: CH₃F, 340 ± 70; CH₃CHF₂, 240 ± 50; CH₂FCl, 110 ± 25; CHFCl₂, 21 ± 4; CHCl₂CF₃, 14 ± 3; CHFClCF₃, 2.7 ± 0.6; CH₃CFCl₂, 2.4 ± 0.5; CHF₂Cl, 2.0 ± 0.4; CH₂FCF₃, 1.6 ± 0.3; CH₃CF₂Cl, 0.37 ± 0.08; and CHF₂CF₃, 0.24 ± 0.05. These Cl atom reaction rate constants are compared with literature data and with the corresponding OH radical reaction rate constants. © John Wiley & Sons, Inc.     

Rate coefficients for the gas-phase reactions of bromine radicals with a series of alkenes,dienes, and aromatic hydrocarbons at 298 ± 2 K

Using the relative kinetic method rate coefficients have been determined for the gas-phase reaction of bromine (Br) radicals with a series of alkenes, chloroalkenes, dienes, and aromatic hydrocarbons in 1000 mbar of synthetic air at 298 ± 2 K. Both the UV photolysis of CH₂Br₂ (λ = 254 nm) and the visible photolysis of Br₂ (320 ≤ λ ≤ 480) were used to generate Br radicals. For the alkenes and dienes the following rate coefficients were obtained (in units of 10⁻¹² cm³ molecule⁻¹ s⁻¹): trans-2-butene 9.26 ± 1.85; 2-methyl-1-butene 15.20 ± 3.00; 2-methyl-2-butene 19.10 ± 3.80; 2,3-dimethyl-2-butene 28.20 ± 5.60; α-pinene 22.20 ± 4.40. β-pinene 28.60 ± 5.70; 1,3-butadiene 57.50 ± 11.50; isoprene 74.20 ± 14.80; and 2,3-dimethyl-1,3-butadiene 81.7 ± 16.30. For the chloroalkenes and aromatic hydrocarbons the following rate coefficients were obtained (in units of 10⁻¹³ cm³ molecule⁻¹ s⁻¹): chloroethene 7.37 ± 1.92; 1,1-dichloroethene 3.66 ± 0.73; trichloroethene 0.90 ± 0.18; tetrachloroethene ≤ 0.1; benzene ≤ 0.10; toluene ≤ 0.10; p-xylene ≤ 0.10; and furan ≤ 0.10. With the exception of trans-2-butene, this study represents the first determination of the rate coefficients for all of the compounds. © 1996 John Wiley & Sons, Inc.     

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

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[5.2.1.0^2,6]decane, 11.4 ± 0.4; and tricyclo[3.3.1.1^3,7]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.     

Kinetics of the gas-phase reactions of NO3 radicals with a series of aromatics at 296 ± 2 K

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.     

Rate constants for the gas-phase reactions of O3 with a series of cycloalkenes and α,β-unsaturated ketones at 296 ± 2 K

The kinetics of the gas-phase reactions of O₃ with a series of alkenes and two α,β-unsaturated ketones have been investigated at atmospheric pressure (ca. 740 torr) of air and 296 ± 2 K, using a relative rate method in the presence of sufficient cyclohexane to scavenge OH radicals generated in these reactions. Combined with our previous relative rate measurements (Int. J. Chem. Kinet., 24, 803 (1992)), the rate constants obtained relative to k(O₃ + propene) = 1.00 were: 3-penten-2-one, 3.62 ± 0.16; 2-cyclohexen-1-one, <0.19; bicyclo[2.2.2]-2-octene, 7.44 ± 0.48; 1,3-cycloheptadiene, 16.1 ± 1.1; cycloheptene, 23.7 ± 1.6; 1,3-cyclohexadiene, 134 ± 13; bicyclo[2.2.1]-2-heptene, 170 ± 16; and bicyclo[2.2.1]-2,5-heptadiene, 390 ± 36. The resulting rate constants then lead to a self-consistent set of room temperature data for the reactions of O₃ with these alkenes and α,β-unsaturated ketones. These rate constants are compared with the literature data, and the effects of ring size discussed. © 1994 John Wiley & Sons, Inc.     

Rate constants for the gas-phase reactions of O3 with selected organics at 296 K

Rate constants for the gas-phase reactions of O₃ with ethene, propene, 1-hexene, 1-heptene, styrene, o-, m-, and p-cresol, o- and m-xylene, benzylchloride, acrylonitrile, and trichloroethene have been determined at 296 ± 2 K. The rate constants ranged from <5 × 10^?21 cm³ molecule^?1 s^?1 for m-xylene to 2.16 × 10^?17 cm³ molecule^?1 s^?1 for styrene, with those for ethene, propene, and 1-hexene being in excellent agreement with literature data.     

Rate constants for the gas-phase reactions of Cl-atoms with C2?C8 alkanes at T = 296 ± 2 K

Relative rate constants for the gas-phase reactions of Cl-atom with thirteen atmospherically interesting alkanes (C₂? C₈) have been determined at 296 ± 2 K based on GC/FID measurements of their relative decays in the UV (λ ≥ 300 nm) photolysis of mixtures containing Cl₂ and the entire series of the selected alkanes in the mtorr range in 750 torr of N₂. The following absolute rate constants (in units of 10^?10 cm³ molecule^?1 s^?1) have been derived from the relative rate constants combined with the value of 1.94 × 10^?10 cm³ molecule^?1 s^?1 for the Cl + n-butane reaction: ethane (0.57 ± 0.05); propane (1.27 ± 0.02); 2-methyl propane (1.30 ± 0.01), 2-methyl butane ((1.96 ± 0.02)), n-pentane (2.50 ± 0.02); 2,3-dimethyl butane (2.00 ± 0.06); 2-methyl pentane (2.58 ± 0.08); n-hexane (3.05 ± 0.04); 2-methyl hexane (3.12 ± 0.04); n-heptane (3.65 ± 0.06); 2,2,4-trimethyl pentane (2.25 ± 0.08); and n-octane (4.09 ± 0.12). The uncertainties indicated are two least-squares standard deviations (2σ). These rate constants are compared with literature values and their applicability to Arctic tropospheric conditions is discussed. © 1995 John Wiley & Sons, Inc.     

Rate constants for the reaction of OH radicals with a series of alkanes and alkenes at 299 ± 2 K

Using methyl nitrite photolysis in air as a source of hydroxyl radicals, relative rate constants for the reaction of OH radicals with a series of alkanes and alkenes have been determined at 299 ± 2 K. The rate constant ratios obtained are: relative to n-hexane = 1.00, neopentane 0.135 ± 0.007, n-butane 0.453 ± 0.007, cyclohexane 1.32 ± 0.04; relative to cyclohexane = 1.00, n-butane 0.341 ± 0.002, cyclopentane 0.704 ± 0.007, 2,3-dimethylbutane 0.827 ± 0.004, ethene 1.12 ± 0.05; relative to propene = 1.00, 2-methyl-2-butene 3.43 ± 0.13, isoprene 3.81 ± 0.17, 2,3-dimethyl-2-butene 4.28 ± 0.21. These relative rate constants are placed on an absolute basis using previous absolute rate constant data and are compared and discussed with literature data.     

Rate constants for the reaction of OH radicals with a series of alkenes and dialkenes at 295 ± 1 K

Using a relative rate technique, rate constants for the gas phase reactions of the OH radical with n-butane, n-hexane, and a series of alkenes and dialkenes, relative to that for propene, have been determined in one atmosphere of air at 295 ± 1 K. The rate constant ratios obtained were (propene = 1.00): ethene, 0.323 ± 0.014; 1-butene, 1.19 ± 0.06; 1-pentene, 1.19 ± 0.05; 1-hexene, 1.40 ± 0.04; 1-heptene, 1.51 ± 0.06; 3-methyl-1-butene, 1.21 ± 0.04; isobutene, 1.95 ± 0.09; cis-2-butene, 2.13 ± 0.05; trans-2-butene, 2.43 ± 0.05; 2-methyl-2-butene, 3.30 ± 0.13; 2,3-dimethyl-2-butene, 4.17 ± 0.18; propadiene, 0.367 ± 0.036; 1,3-butadiene, 2.53 ± 0.08; 2-methyl-1,3-butadiene, 3.81 ± 0.15; n-butane, 0.101 ± 0.012; and n-hexane, 0.198 ± 0.017. From a least-squares fit of these relative rate data to the most reliable literature absolute flash photolysis rate constants, these relative rate constants can be placed on an absolute basis using a rate constant for the reaction of OH radicals with propene of 2.63 × 10^?11 cm³ molecule^?1 s^?1. The resulting rate constant data, together with previous relative rate data from these and other laboratories, lead to a self-consistent data set for the reactions of OH radicals with a large number of organics at room temperature.     

Rate constants for the gas-phase reactions of selected dibasic esters with the OH radical

Using a relative rate method, rate constants have been measured for the gas-phase reactions of the OH radical with the dibasic esters dimethyl succinate [CH₃OC(O)CH₂CH₂C(O)OCH₃], dimethyl glutarate [CH₃OC(O)CH₂CH₂CH₂C(O)OCH₃], and dimethyl adipate [CH₃OC(O)CH₂CH₂CH₂CH₂C(O)OCH₃] at 298±3 K. The rate constants obtained were (in units of 10⁻¹² cm³ molecule⁻¹ s⁻¹): dimethyl succinate, 1.4±0.6; dimethyl glutarate, 3.3±1.1; and dimethyl adipate, 8.4±2.5, where the indicated errors include the estimated overall uncertainty of ±25% in the rate constant for cyclohexane, the reference compound. The calculated tropospheric lifetimes of these dibasic esters due to gas-phase reaction with the OH radical range from 1.4 days for dimethyl adipate to 8.3 days for dimethyl succinate for a 24 h average OH radical concentration of 1.0×10⁶ molecule cm⁻³. © 1998 John Wiley & Sons, Inc. Int J Chem Kinet: 30: 471–474, 1998     

Kinetics of the gas-phase reactions of OH radicals with alkyl nitrates at 299 ± 2 K

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.     

Rate constants for the reactions of the OH radical with the propyl and butyl nitrates and 1-nitrobutane at 298 ± 2 k

Using a relative rate method, rate constants for the gas-phase reactions of the OH radical with 1- and 2-propyl nitrate, 1- and 2-butyl nitrate and 1-nitrobutane have been determined in the presence of one atmosphere of air at 298 ± 2 K. Using rate constants for the reactions of the OH radical with propane and cyclohexane of 1.15 × 10^?12 and 7.49 × 10^?12 cm³ molecule^?1 s^?1, respectively, following rate constants (in units of 10^?12 cm³ molecule^?1 s^?1) were obtained: 1-propyl nitrate, 0.62; 2-propyl nitrate, 0.41; 1-butyl nitrate, 1.78; 2-butyl nitrate, 0.93; and 1-nitrobutane, 1.35. These rate constants are compared and discussed with the literature data.