Products of the Gas-Phase Reactions of Linalool with OH Radicals, NO₃ Radicals, and O₃

Abstract

Linalool [(CH 3 ) 2 C CHCH 2 CH 2 C(CH 3 )(OH)CH CH 2 ] is a terpene derivative emitted from vegetation, including orange blossoms and certain trees and vegetation in the Mediter ranean area. Linalool reacts rapidly in the gas phase in the troposphere with OH radicals, NO 3 radicals, and O 3, with a calculated lifetime due to these reactions of ∼1 h or less. The products of these gas-phase reactions have been studied in ∼6500−7900-L Teflon chambers using gas chro matography, in situ Fourier transform infrared absorption spectroscopy, and direct air sampling atmospheric pres sure ionization tandem mass spectrometry. The products identified and their formation yields are as follows: from the OH radical reaction, acetone, 0.505 ± 0.047; 6-methyl-5-hepten-2-one, 0.068 ± 0.006; 4-hydroxy-4-methyl-5-hexen-1-al (or its cyclized isomer), 0.46 ± 0.11; from the NO 3 radical reaction, acetone, 0.225 ± 0.052; 4-hydroxy-4-methyl-5-hexen-1-al (or its cyclized isomer), 0.191 ± 0.051; and a non-quantified nitrooxycarbonyl; from the O 3 reaction, acetone, 0.211 ± 0.024; 4-hydroxy-4-methyl-5-hexen-1-al (or its cyclized isomer), 0.85 ± 0.14; 5-ethenyldihydro-5-methyl-2(3 H )-furanone, 0.126 ± 0.025; and HCHO, 0.36 ± 0.06. The formation routes to these products and the reaction mechanisms are discussed. Despite the complexity of linalool, a C 10 -hydroxydiene, the reaction products observed and quantified account for a significant fraction of the carbon reacted (especially for the OH radical and O 3 reactions), with the carbon balances being 53 ± 8% for the OH radical reaction in the presence of NO, 20 ± 4% (plus the non-quantified, but anticipated to be major, nitrooxycarbonyl) for the NO 3 radical reaction, and 78 ± 10% for the O 3 reaction.