Gas-phase reaction of (E)-β-farnesene with ozone: Rate coefficient and carbonyl products

The gas-phase ozonolysis of (E)-beta-farnesene was investigated in a 3.91 m(3) atmospheric simulation chamber at 296 +/- 2 K and relative humidity of around 0.1%. The relative rate method Was used to determine the reaction rate coefficient of (4.01 +/- 0.17) x 10(-16) cm(3) molecule(-1) s(-1), where the indicated errors are two least-squares standard deviations and do not include uncertainties in the rate coefficients for the reference compounds (gamma-terpinene, cis-cyclooctene and 1,5-cyclooctadiene). Gas phase carbonyl products were collected using a denuder sampling technique and analyzed with GC/MS following derivatization with O-(2,3,4,5,6-pentafluorobenzyl) hydroxylamine (PFBHA). The reaction products detected were acetone, 4-oxopentanal, methylglyoxal, 4-methylenehex-5-enal, 6-methylhept-5-en-2-one, and (E)-4-methyl-8-methylenedeca-4,9-dienal. A detailed mechanism for the gas-phase ozonolysis of(E)-beta-farnesene is proposed, which accounts for all of the products observed in this study. The results of this work indicate that the atmospheric reaction of (E)-beta-farnesene with ozone has a lifetime of around 1 h and is another possible source of the ubiquitous carbonyls, acetone, 4-oxopentanal and 6-methylhept-5-en-2-one in the atmosphere. (C) 2009 Elsevier Ltd. All rights reserved.