The kinetics of the reaction of nitrous acid (HONO) with nitric acid (HNO3), nitrate radicals (NO 3 ) and dinitrogen pentoxide (N205 ) have been studied using Fourier transform infrared spectroscopy. Experiments were performed at 700 torr total pressure using synthetic air or argon as diluents. From the observed decay of HONO in the presence of HNO 3 a rate constant of k < 7 x 10 -19 cm 3 molecule -I s -I was derived for the reaction of HONO with HNO 3. From the observed decay of HONO in the presence of mixtures ofN205 and NO 2 we have also derived upper limits for the rate constants of the reactions of HONO with NO 3 and N205 of 2 x 10 -~s and 7 x 10 -19 cm 3 molecule -I s -1, respectively. These results are discussed with respect to previous studies and to the atmospheric chemistry of HONO.

The mechanisms for the Cl‐initiated and OH‐initiated atmospheric oxidation of t‐butyl alcohol (TBA), methyl t‐butyl ether (MTBE), and dimethyl ether (DME) have been determined. For TBA the only products observed are equimolar amounts of H2CO and acetone, and its atmospheric oxidation can be represented by (7), The mechanism for the atmospheric oxidation of DME is also straight forward, with the only observable product being methyl formate, The mechanism for the atmospheric oxidation of MTBE is more complex, with observable products being t‐butyl formate (TBF) and H2CO. Evidence is presented also for the formation of 2‐methoxy‐2‐methyl propanal (MMP), which is highly reactive and presumably oxidized to products. The atmospheric oxidation of MTBE can be represented by (9) and (10), In terms of atmospheric reactivity, DME, TBA, and MTBE all compare favorably with methanol. In terms of rate of reaction in the atmosphere, DME, MTBE, and TBA are 1.4, 0.40, and 0.28 times as reactive as CH3OH towards OH on a per carbon basis. With regard tochemistry, atmospheric oxidation of CH3OH yields highly reactive H2CO as the sole carbon‐containing product. In contrast, only 25% of the carbon in TBA is converted to H2CO, with the balance yielding unreactive acetone. For DME, all the carbon is converted to methyl formate which is unreactive. Finally, for MTBE, 60% is converted to unreactive TBF while the remaining 40% produces highly reactive MMP. Final assessment of the impact of these materials on the atmospheric reactivity of vehicle emissions requires the determination of their emissions rates under realistic operating conditions.

The relative rate technique has been used to determine the rate constants for the reaction of chlorine atoms with a series of oxygenated organic species. Experiments were performed a t 295 t 2 K and atmospheric pressure of synthetic air or nitrogen. The decay rates of the organic species were measured relative to that of ethane or n-butane. Using rate constants of 5.7 x lo-" cm3 molecule-'s-', and 2.25 x lo-'' cm3 molecule-' s-l for the reaction of C1 with ethane and n-butane respectively the following rate constants were derived, in units of lo-" cm3 molecule-' s-': propane, (16.0 2 0.4); i-butane, (15.1 -t 0.9); n-pentane, (31.0 .t 1.6); n-hexane, (34.5 2 2.3); cyclohexane, (36.1 f 1.5); methanol, (4.57 2 0.40); ethanol, (8.45 t 0.91); n-propanol, (14.4 f 1.2); tbutylalcohol, (3.26 f 0.19); acetaldehyde, (8.45 t 0.79); propionaldehyde, (11.3 2 0.9); dimethylether, (20.5 t 0.8); diethylether, (35.6 t 2.8); and methyl-t-butylether, (16.6 2 1.2). Quoted errors represent 20, and do not include any errors due to uncertainties in the rate constants used to place our relative measurements on an absolute basis. The results are discussed with respect to the mechanisms of these reactions and to previous literature data.

Ethers are being increasingly used as motor fuel additives to increase the octane number and to reduce CO emissions. Since their reaction with hydroxyl radicals (OH) is a major loss process for these oxygenated species in the atmosphere, we have conducted a relative rate study of the kinetics of the reactions of OH radicals with a series of ethers and report the results of these measurements here. Experiments were performed under simulated atmospheric conditions; atmospheric pressure (2740 torr) in synthetic air a t 295 K. Using rate constants of 2.53 x lo-", and 1.35 x lo-'' cm3 molecule-' s-l for the reaction of OH radicals with n-butane and diethyl ether, the following rate constants were derived, in units of lo-" cm3 molecule-' sf': dimethylether, (0.232 2 0.023); di-n-propylether, (1.97 2 0.08); di-n-butylether, (2.74 2 0.32); di-n-pentylether, (3.09 5 0.26); methyl-t-butylether, (0.324 2 0.008); methyl-nbutylether, (1.29 * 0.03); ethyl-n-butylether, (2.27 2 0.09); and ethyl-t-butylether, (0.883 0.026). Quoted errors represent 2u from the least squares analysis and do not include any systematic errors associated with uncertainties in the reference rate constants used to place our relative measurements on an absolute basis. The implications of these results for the atmospheric chemistry of ethers are discussed.