Gas‐phase ozonolysis: Rate coefficients for a series of terpenes and rate coefficients and OH yields for 2‐methyl‐2‐butene and 2,3‐dimethyl‐2‐butene

Abstract

AbstractThe kinetics of the gas‐phase reactions of O3with a series of selected terpenes has been investigated under flow‐tube conditions at a pressure of 100 mbar synthetic air at 295 ± 0.5 K. In the presence of a large excess ofm‐xylene as an OH radical scavenger, rate coefficientsk(O3+terpene) were obtained with a relative rate technique, (unit: cm3molecule−1s−1, errors represent 2σ): α‐pinene: (1.1 ± 0.2) × 10−16,3Δ‐carene: (5.9 ± 1.0) × 10−17, limonene: (2.5 ± 0.3) × 10−16, myrcene: (4.8 ± 0.6) × 10−16,trans‐ocimene: (5.5 ± 0.8) × 10−16, terpinolene: (1.6 ± 0.4) × 10−15and α‐terpinene: (1.5 ± 0.4) × 10−14. Absolute rate coefficients for the reaction of O3with the used reference substances (2‐methyl‐2‐butene and 2,3‐dimethyl‐2‐butene) were measured in a stopped‐flow system at a pressure of 500 mbar synthetic air at 295 ± 2 K using FT‐IR spectroscopy, (unit: cm3molecule−1s−1, errors represent 2σ ): 2‐methyl‐2‐butene: (4.1 ± 0.5) × 10−16and 2,3‐dimethyl‐2‐butene: (1.0 ± 0.2) × 10−15. In addition, OH radical yields were found to be 0.47 ± 0.04 for 2‐methyl‐2‐butene and 0.77 ± 0.04 for 2,3‐dimethyl‐2‐butene. © 2002 Wiley Periodicals, Inc. Int J Chem Kinet 34: 394–403, 2002