Atmospheric chemistry of three C-10 alkanes

Kinetics and products of the gas-phase reactions of OH radicals with the C- 10-alkanes n-decane, 3,4-diethylhexane and n-butylcyclohexane have been inv estigated at 296 +/- 2 K and atmospheric pressure of air. Gas chromatograph y with flame ionization detection (GC-FID) and combined gas chromatography -mass spectrometry (GC-MS) were used to identify and quantify alkyl nitrate and carbonyl products, and in situ atmospheric pressure ionization tandem mass spectrometry was employed to identify and quantify, relative to intern al standards, hydroxycarbonyl and hydroxynitrate products. Using a relative rate method, rate constants for reactions of the OH radical with n-decane, 3,4-diethylhexane and n-butylcyclohexane were measured and (in units of 10 (-12) cm(3) molecule(-1) s(-1)) were 12.5 +/- 0.4, 7.43 +/- 0.48 and 15.8 /- 0.6, respectively, where the errors do not include uncertainties in the rate constant for the n-octane reference compound. The products identified and quantified were: 2-, 3-, 4-, and 5-decyl nitrate, hydroxycarbonyls and hydroxynitrates from the n-decane reaction; acetaldehyde, propanal, 3-penta none, 3-pentyl nitrate, C-10 alkyl nitrates, hydroxycarbonyls, and hydroxyn itrates from the 3,4-diethylhexane reaction; and butanal, cyclohexanone, C- 10 alkyl nitrates, hydroxycarbonyls and hydroxynitrates from the n-butylcyc lohexane reaction. The observed gas-phase products are generally in accord with expectations, and account for a significant fraction of the total prod ucts.