Products of the gas-phase reactions of the OH radical with n-butyl methyl ether and 2-isopropoxyethanol:: Reactions of ROC(O)< radicals

The products of the gas-phase reactions of the OH radical with n-butyl methyl ether and 2-isopropoxyethanol in the presence of NO have been investigated at 298 +/- 2 K and 740 Torr total pressure of air by gas chromatography and in situ atmospheric pressure ionization tandem mass spectrometry. The products observed from n-butyl methyl ether were methyl Formate, propanal, butanal, methyl butyrate, and CH3C(O)CH2CH2OCH3 and/or CH3CH2C(O)CH2OCH3, with molar formation yields of 0.51 +/- 0.11, 0.43 +/- 0.06, 0.045 +/- 0.010, similar to 0.016, and 0.19 +/- 0.04, respectively. Additional products of molecular weight 118, 149 and 165 were observed by API-MS/MS analyses, with those of molecular weight 149 and 165 being identified as organic nitrates. The products observed and quantified from 2-isopropoxyethanol were isopropyl Formate and 2-hydroxyethyl acetate, with molar formation yields of 0.57 +/- 0.05 and 0.44 +/- 0.05, respectively. For both compounds, the majority of the reaction products and reaction pathways are accounted for, and detailed reaction mechanisms are presented. The results of this product study are combined with previous literature product data to investigate the tropospheric reactions of R1R2C((O)over dot)OR radicals formed from ethers and glycol ethers, leading to a revised estimation method for the calculation of reaction rates of alkoxy radicals. (C) 1999 John Wiley & Sons, Inc.