Rate coefficients for the gas‐phase reaction of OH radicals with selected dihydroxybenzenes and benzoquinones

Rate coefficients have been determined for the gas‐phase reaction of the hydroxyl (OH) radical with the aromatic dihydroxy compounds 1,2‐dihydroxybenzene, 1,2‐dihydroxy‐3‐methylbenzene and 1,2‐dihydroxy‐4‐methylbenzene as well as the two benzoquinone derivatives 1,4‐benzoquinone and methyl‐1,4‐benzoquinone. The measurements were performed in a large‐volume photoreactor at (300 ± 5) K in 760 Torr of synthetic air using the relative kinetic technique. The rate coefficients obtained using isoprene, 1,3‐butadiene, and E‐2‐butene as reference hydrocarbons are k_OH(1,2‐dihydroxybenzene) = (1.04 ± 0.21) × 10⁻¹⁰ cm³ s⁻¹, k_OH(1,2‐dihydroxy‐3‐methylbenzene) = (2.05 ± 0.43) × 10⁻¹⁰ cm³ s⁻¹, k_OH(1,2‐dihydroxy‐4‐methylbenzene) = (1.56 ± 0.33) × 10⁻¹⁰ cm³ s⁻¹, k_OH(1,4‐benzoquinone) = (4.6 ± 0.9) × 10⁻¹² cm³ s⁻¹, k_OH(methyl‐1,4‐benzoquinone) = (2.35 ± 0.47) × 10⁻¹¹ cm³ s⁻¹. This study represents the first determination of OH radical reaction‐rate coefficients for these compounds. © 2000 John Wiley & Sons, Inc. Int J Chem Kinet 32: 696–702, 2000     

Direct measurement of the C2H5C(O)O2 + NO reaction rate coefficient using chemical ionization mass spectrometry

The rate coefficient for the reaction of the peroxypropionyl radical (C₂H₅C(O)O₂) with NO was measured with a laminar flow reactor over the temperature range 226–406 K. The C₂H₅C(O)O₂ reactant was monitored with chemical ionization mass spectrometry. The measured rate coefficients are k(T) = (6.7 ± 1.7) × 10⁻¹² exp{(340 ± 80)/T} cm³ molecule⁻¹ s⁻¹ and k(298 K) = (2.1 ± 0.2) × 10⁻¹¹ cm³ molecule⁻¹ s⁻¹. Our results are comparable to recommended rate coefficients for the analogous CH₃C(O)O₂ + NO reaction. Heterogeneous effects, pressure dependence, and concentration gradients inside the flow reactor are examined. © 1999 John Wiley & Sons, Inc. Int J Chem Kinet: 31: 221–228, 1999     

Electrochemical behavior of 5-amino-1,10-phenanthroline and oxidative electropolymerization of tris[5-amino-1,10-phenanthroline]iron(II)

The electrochemical behavior of 5-amino-1,10-phenanthroline and tris[5-amino-1,10-phenanthroline]-iron(II) at carbon paste, glassy carbon, and platinum electrodes is reported. The iron complex undergoes electrochemically induced oxidative polymerization from acetonitrile solutions and the resulting polymers are very stable. Charge transport through the polymer films occurs with a charge transfer diffusion coefficient, D_ct, equal to 3.1 × 10⁻⁸ cm² s⁻¹ corresponding to an electron self-exchange rate of 5.2×10⁷M⁻¹ s⁻¹. The activation energy and the entropy change for the charge transfer diffusion process are (approximate values) 32.0 ± 0.12 kJ mol⁻¹ and −24.7 ± 0.4 J K⁻¹ mol⁻¹, respectively.     

Shock tube study of monomethylamine thermal decomposition and NH2 high temperature absorption coefficient

CH₃NH₂ thermal decomposition is shown to provide a suitable NH₂ radical source for spectroscopic and kinetic shock tube studies. Using this precursor, the absorption coefficient of the NH₂ radical at a detection wavelength of 16739.90 cm⁻¹ has been determined. In the temperature range 1600–2000K the low‐pressure absorption coefficient is described by the polynominal equation: k_NH2=3.953×10¹⁰/T ³+7.295×10⁵/T ²−1.549×10³/T [atm⁻¹ cm⁻¹] The uncertainty of the determined absorption coefficient is estimated to be ±10%. The rate of the thermal decomposition reaction CH₃NH₂+M → CH₃+NH₂+M is determined over the temperature range 1550–1900 K and at pressures near 1.6 atm. The rate coefficient was found to be: k₁=2.51×10¹⁶ exp(−28430/T) [cm³ mol⁻¹ s⁻¹] The uncertainty of the determined rate coefficients is estimated to be ±20%. © 1999 John Wiley & Sons, Inc. Int J Chem Kinet 31: 323–330, 1999     

Temperature dependence of the reaction of NO with CFCl2CH2O2 and CH3CFClO2 radicals

The reaction of NO with the peroxy radical CFCl₂CH₂O₂, and with CH₃CFClO₂ was investigated at 8(SINGLEBOND)20 torr and 263(SINGLEBOND)321 K by UV flash photolysis of CFCl₂CH₃/O₂/NO gas mixtures. The kinetics were determined from observations of the growth rate of the CFCl₂CH₂O radical and the decay rate of NO by time-resolved mass spectrometry. The temperature dependence of the bimolecular rate coefficients, with their statistical uncertainties, can be expressed as (2.9 ± 0.7) e^(435±96)/T × 10⁻¹² cm³ molecule ⁻¹s⁻¹, or (1.3 ± 0.2) (T/300)^{&minus(1.5±0.2)} × 10⁻¹¹ cm³ molecule⁻¹ s⁻¹ for NO + CFCl₂CH₂O₂, and (3.3 ± 0.6)e^(516±73)/T × 10⁻¹² cm³ molecule⁻¹ s⁻¹, or (2.0 ± 0.3) (T/300)^{&minus(1.8±0.3)} × 10⁻¹¹ cm³ molecule⁻¹ s⁻¹ for NO + CH₃CFClO₂. No pressure dependence of the rate coefficients could be detected over the 8(SINGLEBOND)20 torr range investigated. © 1996 John Wiley & Sons, Inc.     

Temperature-dependent kinetics studies of the reactions of C2H5O2 and n-C3H7O2 radicals with NO

The rate coefficients for the gas-phase reactions of C₂H₅O₂ and n-C₃H₇O₂ radicals with NO have been measured over the temperature range of (201–403) K using chemical ionization mass spectrometric detection of the peroxy radical. The alkyl peroxy radicals were generated by reacting alkyl radicals with O₂, where the alkyl radicals were produced through the pyrolysis of a larger alkyl nitrite. In some cases C₂H₅ radicals were generated through the dissociation of iodoethane in a low-power radio frequency discharge. The discharge source was also tested for the i-C₃H₇O₂ + NO reaction, yielding k_{298 K} = (9.1 ± 1.5) × 10⁻¹² cm³ molecule⁻¹ s⁻¹, in excellent agreement with our previous determination. The temperature dependent rate coefficients were found to be k(T) = (2.6 ± 0.4) × 10⁻¹² exp{(380 ± 70)/T} cm³ molecule⁻¹ s⁻¹ and k(T) = (2.9 ± 0.5) × 10⁻¹² exp{(350 ± 60)/T} cm³ molecule⁻¹ s⁻¹ for the reactions of C₂H₅O₂ and n-C₃H₇O₂ radicals with NO, respectively. The rate coefficients at 298 K derived from these Arrhenius expressions are k = (9.3 ± 1.6) × 10⁻¹² cm³ molecule⁻¹ s⁻¹ for C₂H₅O₂ radicals and k = (9.4 ± 1.6) × 10⁻¹² cm³ molecule⁻¹ s⁻¹ for n-C₃H₇O₂ radicals. © 1996 John Wiley & Sons, Inc.     

Rate coefficients for the reactions of chlorine atoms with methanol and acetaldehyde

Rate coefficients have been measured for the reactions of Cl atoms with methanol (k₁) and acetaldehyde (k₂) using both absolute (laser photolysis with resonance fluorescence) and relative rate methods at 295 ± 2 K. The measured rate coefficients were (units of 10⁻¹¹ cm³ molecule⁻¹ s⁻¹): absolute method, k₁ = (5.1 ± 0.4), k₂ = (7.3 ± 0.7); relative method k₁ = (5.6 ± 0.6), k₂ = (8.4 ± 1.0). Based on a critical evaluation of the literature data, the following rate coefficients are recommended: k₁ = (5.4 ± 0.9) × 10⁻¹¹ and k₂ = (7.8 ± 1.3) × 10⁻¹¹ cm³ molecule⁻¹ s⁻¹ (95% confidence limits). The results significantly improve the confidence in the database for reactions of Cl atoms with these oxygenated organics. Rate coefficients were also measured for the reactions of Cl₂ with CH₂OH, k₅ = (2.9 ± 0.6) × 10⁻¹¹ and CH₃CO, k₆ = (4.3 ± 1.5) × 10⁻¹¹ cm³ molecule⁻¹ s⁻¹, by observing the regeneration of Cl atoms in the absence of O₂. Based on these results and those from a previous relative rate study, the rate coefficient for CH₃CO + O₂ at the high pressure limit is estimated to be (5.7 ± 1.9) × 10⁻¹² cm³ molecule⁻¹ s⁻¹. © 1999 John Wiley & Sons, Inc. Int J Chem Kinet 31: 776–784, 1999     

Kinetic study of gas-phase reactions of pinonaldehyde and structurally related compounds

Rate constants for the reactions of OH, NO₃, and O₃ with pinonaldehyde and the structurally related compounds 3-methylbutanal, 3-methylbutan-2-one, cyclobutyl-methylketone, and 2,2,3-trimethyl-cyclobutyl-1-ethanone have been measured at 300±5 K using on-line Fourier transform infrared spectroscopy. The rate constants obtained for the reactions with pinonaldehyde were: k_OH=(9.1±1.8)×10⁻¹¹ cm³ molecule⁻¹ s⁻¹, k_NO3=(5.4±1.8)×10⁻¹⁴ cm³ molecule⁻¹ s⁻¹, and k_O3=(8.9±1.4)×10⁻²⁰ cm³ molecule⁻¹ s⁻¹. The results obtained indicate a chemical lifetime of pinonaldehyde in the troposphere of about two hours under typical daytime conditions, [OH]=1.6×10⁶ molecule cm⁻³. © 1997 John Wiley & Sons, Inc. Int J Chem Kinet 29: 527–533, 1997.     

Determination of the rate constants for the gas-phase reactions of methyl butenol with OH radicals,ozone, NO3 radicals,and Cl atoms

Using a relative rate method, rate constants for the gas-phase reactions of 2-methyl-3-buten-2-ol (MBO) with OH radicals, ozone, NO₃ radicals, and Cl atoms have been investigated using FTIR. The measured values for MBO at 298±2 K and 740±5 torr total pressure are: k_OH=(3.9±1.2)×10⁻¹¹ cm³ molecule⁻¹ s⁻¹, k_O3=(8.6±2.9)×10⁻¹⁸ cm³ molecule⁻¹ s⁻¹, k=(8.6±2.9)×10⁻¹⁵ cm³ molecule⁻¹ s⁻¹, and k_Cl=(4.7±1.0)×10⁻¹⁰ cm³ molecule⁻¹ s⁻¹. Atmospheric lifetimes have been estimated with respect to the reactions with OH, O₃, NO₃, and Cl. The atmospheric relevance of this compound as a precursor for acetone is, also, briefly discussed. © 1998 John Wiley & Sons, Inc. Int J Chem Kinet: 30: 589–594, 1998     

Kinetics of the gas-phase reactions of the oh radical with selected glycol ethers,glycols, and alcohols

Using a relative rate method, rate constants have been measured for the gas-phase reactions of the OH radical with 1-hexanol, 1-methoxy-2-propanol, 2-butoxyethanol, 1,2-ethanediol, and 1,2-propanediol at 296±2 K, of (in units of 10⁻¹² cm³ molecule⁻¹ s⁻¹): 15.8±3.5; 20.9±3.1; 29.4±4.3; 14.7±2.6; and 21.5±4.0, respectively, where the error limits include the estimated overall uncertainties in the rate constants for the reference compounds. These OH radical reaction rate constants are higher than certain of the literature values, by up to a factor of 2. Rate constants were also measured for the reactions of 1-methoxy-2-propanol and 2-butoxyethanol with NO₃ radicals and O₃, with respective NO₃ radical and O₃ reaction rate constants (in cm³ molecule⁻¹ s⁻¹ units) of: 1-methoxy-2-propanol, (1.7±0.7)×10⁻¹⁵, and <1.1×10⁻¹⁹; and 2-butoxyethanol, (3.0±1.2)×10⁻¹⁵, and <1.1×10⁻¹⁹. The dominant tropospheric loss process for the alcohols, glycols, and glycol ethers studied here is calculated to be by reaction with the OH radical, with lifetimes of 0.4–0.8 day 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: 533–540, 1998     

Atmospheric chemistry of di-tert-butyl ether: Rates and products of the reactions with chlorine atoms,hydroxyl radicals,and nitrate radicals

The rate constants for the gas-phase reactions of di-tert-butyl ether (DTBE) with chlorine atoms, hydroxyl radicals, and nitrate radicals have been determined in relative rate experiments using FTIR spectroscopy. Values of k_(DTBE+CI) = (1.4 ± 0.2) × 10⁻¹⁰,k_(DTBE+OH) = (3.7 ± 0.7) × 10⁻¹², and k_(DTBE+N03) = (2.8 ± 0.9) × 10⁻¹⁶ cm³ molecule⁻¹ s⁻¹ were obtained. Tert-butyl acetate was identified as the major product of both Cl atom and OH radical initiated oxidation of DTBE in air in the presence of NO_x. The molar tert-butyl acetate yield was 0.85 ± 0.11 in the Cl atom experiments and 0.84 ± 0.11 in OH radical experiments. As part of this work the rate constant for reaction of Cl atoms with tert-butyl acetate at 295 K was determined to be (1.6 ± 0.3) × 10⁻¹¹ cm³ molecule⁻¹ s⁻¹. The stated errors are two standard deviations (2σ). © 1996 John Wiley & Sons, Inc.     

Cavity ring‐down spectroscopic study of the kinetics of the reactions of FCO radicals with O2 and NO at 295 K

Cavity ring‐down UV absorption spectroscopy was used to study the kinetics of the recombination reaction of FCO radicals and the reactions with O₂ and NO in 4.0–15.5 Torr total pressure of N₂ diluent at 295 K. k(FCO + FCO) is (1.8 ± 0.3) × 10⁻¹¹ cm³ molecule⁻¹ s⁻¹. The pressure dependence of the reactions with O₂ and NO in air at 295 K is described using a broadening factor of Fc = 0.6 and the following low (k₀) and high (k_∞) pressure limit rate constants: k₀(FCO + O₂) = (8.6 ± 0.4) × 10⁻³¹ cm⁶ molecule⁻¹ s⁻¹, k_∞(FCO + O₂) = (1.2 ± 0.2) × 10⁻¹² cm³ molecule⁻¹ s⁻¹, k₀(FCO + NO) = (2.4 ± 0.2) × 10⁻³⁰ cm⁶ molecule⁻¹ s⁻¹, and k_∞ (FCO + NO) = (1.0 ± 0.2) × 10⁻¹² cm³ molecule⁻¹ s⁻¹. The uncertainties are two standard deviations. © 2001 John Wiley & Sons, Inc. Int J Chem Kinet 33: 130–135, 2001     

Atmospheric Chemistry of Camphor

Rate constants have been measured at 296 ± 2 K for the gas‐phase reactions of camphor with OH radicals, NO₃ radicals, and O₃. Using relative rate methods, the rate constants for the OH radical and NO₃ radical reactions were (4.6 ± 1.2) × 10⁻¹² cm³ molecule⁻¹ s⁻¹ and <3 × 10⁻¹⁶ cm³ molecule⁻¹ s⁻¹, respectively, where the indicated error in the OH radical reaction rate constant includes the estimated overall uncertainty in the rate constant for the reference compound. An upper limit to the rate constant for the O₃ reaction of <7 × 10⁻²⁰ cm³ molecule⁻¹ s⁻¹ was also determined. The dominant tropospheric loss process for camphor is calculated to be by reaction with the OH radical. Acetone was identified and quantified as a product of the OH radical reaction by gas chromatography, with a formation yield of 0.29 ± 0.04. In situ atmospheric pressure ionization tandem mass spectrometry (API‐MS) analyses indicated the formation of additional products of molecular weight 166 (dicarbonyl), 182 (hydroxydicarbonyl), 186, 187, 213 (carbonyl‐nitrate), 229 (hydroxycarbonyl‐nitrate), and 243. A reaction mechanism leading to the formation of acetone is presented, as are pathways for the formation of several of the additional products observed by API‐MS. © 2000 John Wiley and Sons, Inc. Int J Chem Kinet 33: 56–63, 2001     

Pulse radiolysis study of the formation and the reactivity of baicalin radical anion,and in comparison with rutin,quercetin and acyrlate ester radical anions in ethanol

The reaction of solvated electrons with baicalin in N₂-saturated ethanol has been studied by pulse radiolysis. The results show that a solvated electron can add to baicalin and generate a baicalin radical anion with a maximum UV absorbance peak at 360 nm. Its molar extinction coefficient at this wavelength is 1.3×10⁴ M⁻¹ cm⁻¹. The rate constant for the build-up of the baicalin radical anion is 1.3(±0.4)×10¹⁰ M⁻¹ s⁻¹. Decay of the radical anion is induced by a proton transfer reaction and a recombination reaction, which involves a pseudo-first-order reaction with rate constant 2.6(±0.4)×10³ s⁻¹ and a second-order reaction with rate constant 1.3(±0.2)×10⁹ M⁻¹ s⁻¹. The effect of acetaldehyde on the decay of the baicalin radical anion was also investigated. Electron transfer between the baicalin radical anion and acetaldehyde was not observed, probably due to the low rate of electron transfer between the baicalin radical anion and acetaldehyde. Reactivity of the rutin, quercetin, baicalin and ethyl acrylate radical anions are also compared.     

Temperature dependence of the rate coefficients for the reaction of chlorine atoms with chloromethanes

Rate coefficients for the reaction of Cl atoms with CH₃Cl (k₁), CH₂Cl₂ (k₂), and CHCl₃ (k₃) have been determined over the temperature range 222–298 K using standard relative rate techniques. These data, when combined with evaluated data from previous studies, lead to the following Arrhenius expressions (all in units of cm³ molecule⁻¹ s⁻¹): k₁ = (2.8 ± 0.3) × 10⁻¹¹ exp(−1200 ± 150/T); k₂ = (1.5 ± 0.2) × 10⁻¹¹ exp(−1100 ± 150/T); k₃ = (0.48 ± 0.05) × 10⁻¹¹ exp(−1050 ± 150/T). Values for k₁ are in substantial agreement with previous measurements. However, while the room temperature values for k₂ and k₃ agree with most previous data, the activation energies for these rate coefficients are substantially lower than previously recommended values. In addition, the mechanism of the oxidation of CH₂Cl₂ has been studied. The dominant fate of the CHCl₂O radical is decomposition via Cl‐atom elimination, even at the lowest temperatures studied in this work (218 K). However, a small fraction of the CHCl₂O radicals are shown to react with O₂ at low temperatures. Using an estimated value for the rate coefficient of the reaction of CHCl₂O with O₂ (1 × 10⁻¹⁴ cm³ molecule⁻¹ s⁻¹), the decomposition rate coefficient for CHCl₂O is found to be about 4 × 10⁶ s⁻¹ at 218 K, with the barrier to its decomposition estimated at 6 kcal/mole. As part of this work, the rate coefficient for Cl atoms with HCOCl was also been determined, k₇ = 1.4 × 10⁻¹¹ exp(−885/T) cm³ molecule⁻¹ s⁻¹, in agreement with previous determinations. © 1999 John Wiley & Sons, Inc. Int J Chem Kinet 31: 515–524, 1999     

Rate constants for the gas‐phase reactions of Cl atoms with a series of ethers

The laser photolysis–resonance fluorescence technique has been used to determine the absolute rate coefficient for the Cl atom reaction with a series of ethers, at room temperature (298 ± 2) K and in the pressure range 15–60 Torr. The rate coefficients obtained (in units of cm³ molecule⁻¹ s⁻¹) are dimethyl ether (1.3 ± 0.2) × 10⁻¹⁰, diethyl ether (2.5 ± 0.3) × 10⁻¹⁰, di‐n‐propyl ether (3.6 ± 0.4) × 10⁻¹⁰, di‐n‐butyl ether (4.5 ± 0.5) × 10⁻¹⁰, di‐isopropyl ether (1.6 ± 0.2) × 10⁻¹⁰, methyl tert‐butyl ether (1.4 ± 0.2) × 10⁻¹⁰, and ethyl tert‐butyl ether (1.5 ± 0.2) × 10⁻¹⁰. The results are discussed in terms of structure–reactivity relationship. © 2000 John Wiley & Sons, Inc. Int J Chem Kinet 32: 105–110, 2000     

Kinetics of the reaction of OH radicals with a series of esters under simulated conditions at 295 K

The rate constants of the isopropyl acetate, n-propyl acetate, isopropenyl acetate, n-propenyl acetate, n-butyl acetate, and ethyl butyrate reactions with OH radicals were determined in purified air under atmospheric conditions, at 750 torr and (295 ± 2) K. A relative rate experimental method was used; n-heptane, n-octane, and n-nonane were the reference compounds, with, respectively, rate constants for the reaction with OH of 7.12 × 10⁻¹², 8.42 × 10⁻¹², and 9.70 × 10⁻¹² molecule⁻¹ cm³s⁻¹. The following rate constants were obtained in units of 10⁻¹² molecule⁻¹ cm³s⁻¹; isopropyl acetate, (3.12 ± 0.29); n-propyl acetate, (1.97 ± 0.24); isopropenyl acetate, (62.53 ± 1.24); n-propenyl acetate, (24.57 ± 0.24); n-butyl acetate, (3.29 ± 0.35); and ethyl butyrate, (4.37 ± 0.42). Tertiary butyl acetate has a low reactivity with OH radicals (<1 × 10⁻¹² molecule⁻¹ cm³s⁻¹). © 1996 John Wiley & Sons, Inc.     

Spectrokinetic study of SF5 and SF5O2 radicals and the reaction of SF5O2 with NO

UV spectra of SF₅ and SF₅O₂ radicals in the gas phase at 295 K have been quantified using a pulse radiolysis UV absorption technique. The absorption spectrum of SF₅ was quantified from 220 to 240 nm. The absorption cross section at 220 nm was (5.5 ± 1.7) × 10⁻¹⁹ cm². When SF₅ was produced in the presence of O₂ an equilibrium between SF₅, O₂, and SF₅O₂ was established. The rate constant for the reaction of SF₅ radicals with O₂ was (8 ± 2) × 10⁻¹³ cm³ molecule⁻¹ s⁻¹. The decomposition rate constant for SF₅O₂ was (1.0 ± 0.5) × 10⁵ s⁻¹, giving an equilibrium constant of K_eq = [SF₅O₂]/[SF₅][O₂] = (8.0 ± 4.5) × 10⁻¹⁸ cm³ molecule⁻¹. The SF₅ O₂ bond strength is (13.7 ± 2.0) kcal mol⁻¹. The SF₅O₂ spectrum was broad with no fine structure and similar to the UV spectra of alkyl peroxy radicals. The absorption cross section at 230 nm was found to (3.7 ± 0.9) × 10⁻¹⁸ cm². The rate constant of the reaction of SF₅O₂ with NO was measured to (1.1 ± 0.3) × 10⁻¹¹ cm³ molecule⁻¹ s⁻¹ by monitoring the kinetics of NO₂ formation at 400 nm. The rate constant for the reaction of F atoms with SF₄ was measured by two relative methods to be (1.3 ± 0.3) × 10⁻¹¹ cm³ molecule⁻¹ s⁻¹. © 1994 John Wiley & Sons, Inc.     

Kinetics of proton transfer in ice via the pH-jump method: Evaluation of the proton diffusion rate in polycrystalline doped ice

The value of the proton diffusion coefficient D_H⁺ in ice was extracted from the diffusion-controlled rate k_D of the proton recombination reaction RO⁻ + H₃O⁺ → k_D ROH + H₂O in polycrystalline doped ice. At −10°C, D_H⁺ was estimated to lie between 3.5×10⁻⁶ and 1.3×10⁻⁵ cm² s⁻¹, well below the corresponding value of (4.1 ± 0.1)×10⁻⁵ cm² s⁻¹ found in supercooled water.     

Kinetics of OH and Cl reactions with a series of aldehydes

The rate constants for the reactions of the OH radicals with a series of aldehydes have been measured in the temperature range 243–372 K, using the pulsed laser photolysis‐pulsed laser induced fluorescence method. The obtained data for propanaldehyde, iso‐butyraldehyde, tert‐butyraldehyde, and n‐pentaldehyde were as follows (in cm³ molecule⁻¹ s⁻¹): (a) in the Arrhenius form: (5.3 ± 0.5) × 10⁻¹² exp[(405 ± 30)/T], (7.3 ± 1.9) × 10⁻¹² exp[(390 ± 78)/T], (4.7 ± 0.8) × 10⁻¹² exp[(564 ± 52)/T], and (9.9 ± 1.9) × 10⁻¹² exp[(306 ± 56)/T]; (b) at 298 K: (2.0 ± 0.3) × 10⁻¹¹, (2.6 ± 0.4) × 10⁻¹¹, (2.7 ± 0.4) × 10⁻¹¹, and (2.8 ± 0.2) × 10⁻¹¹, respectively. In addition, using the relative rate method and alkanes as the reference compounds, the room‐temperature rate constants have been measured for the reactions of chlorine atoms with propanaldehyde, iso‐butyraldehyde, tert‐butyraldehyde, n‐pentaldehyde, acrolein, and crotonaldehyde. The obtained values were (in cm³ molecule⁻¹ s⁻¹): (1.4 ± 0.3) × 10⁻¹⁰, (1.7 ± 0.3)10⁻¹⁰, (1.6 ± 0.3) × 10⁻¹⁰, (2.6 ± 0.3) × 10⁻¹⁰, (2.2 ± 0.3) × 10⁻¹⁰, and (2.6 ± 0.3) × 10⁻¹⁰, respectively. The results are presented and discussed in terms of structure‐reactivity relationships and atmospheric importance. © 2000 John Wiley & Sons, Inc. Int J Chem Kinet 32: 676–685, 2000