No abstract

The products formed by the hydroxyl radical initiated photo-oxidation of diethyl ether have been investigated by irradiating synthetic air mixtures containing diethyl ether and nitrous acid in amounts approaching ppbv levels in a smog chamber. The decay of reactants and formation of products were monitored by gas chromatography, HPLC, and by chemiluminescent analysis. The major products are ethyl formate and formaldehyde, minor products include ethyl acetate, acetaldehyde, peroxyacetyl nitrate, methyl nitrate, and ethyl nitrate. The products observed arise from the decomposition reactions of the l-ethoxyethoxy radical and its reaction with oxygen. One molecule of nitric oxide appears to be oxidized per molecule of diethyl ether reacted. This is lower than would be expected on the basis of the proposed mechanism and possible reasons for the discrepancy are discussed. 0 1993 John Wiley & Sons, Inc.

The rate coefficients for the gas-phase reactions of allyl-, tert-butyl-, cyclopentyl-, and 2-pentylperoxy radicals with NO have been measured at 297 ± 2 K in a flow tube reactor using chemical ionization mass spectrometric (CIMS) detection of the peroxy radical. The hydrocarbon radicals were produced through the dissociation of the parent alkyl iodide in a low-power radio frequency (rf) discharge. The unimolecular decomposition of the c-pentyl radicals in the rf discharge yielded allyl radicals. The peroxy radicals were generated by reacting the hydrocarbon radicals with O2. The rate coefficients were found to be, in units of 10-12 cm3 molecule-1 s-1, 10.5 ± 1.8, 7.9 ± 1.3, 10.9 ± 1.9, and 8.0 ± 1.4 for the reactions of NO with CH2CHCH2O2, t-C4H9O2, c-C5H9O2, and 2-C5H11O2 radicals, respectively. The results of this study together with our previous results for nonsubstituted C1−C3 alkyl peroxy radicals suggest no significant trend in the rate coefficients with size and branching of the radicals. This is in contradiction to some previous studies, which found that the rate coefficients decrease with increasing radical size and complexity. Some implications of this finding for atmospheric chemistry are briefly discussed.

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 k298 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.