Rate constants for the gas‐phase reaction of C 5 C 10 alkenes with ozone

The gas‐phase reaction of ozone with C 5 C 10 alkenes(eight 1‐alkenes, four 1,1‐disubstituted alkenes, and cyclohexene) has been investigated at atmospheric pressure and ambient temperature (285–293 K). Cyclohexane was added to scavenge the hydroxyl radical, which forms as a product of the ozone‐alkene reaction. The reaction rate constants, in units of 10 −18 cm 3 molecule −1 s −1 , are 9.6±1.6 for 1‐pentene, 9.7±1.4 for 1‐hexene, 9.4±0.4 for 1‐heptene, 12.5±0.4 for 1‐octene, 8.0±1.4 for 1‐decene, 3.8±0.6 for 3‐methyl‐1‐pentene, 7.3±0.7 for 4‐methyl‐1‐pentene, 3.9±0.9 for 3,3‐dimethyl‐1‐butene, 13.3±1.4 for 2‐methyl‐1‐butene, 12.5±1.1 for 2‐methyl‐1‐pentene, 10.0±0.3 for 2,3‐dimethyl‐1‐butene, 13.7±0.9 for 2‐ethyl‐1‐butene, and 84.6±1.0 for cyclohexene. Substituent effects on alkene reactivity are examined. Steric effect appear to be important for all 1,1‐disubstituted alkenes as well as for those 1‐alkenes that bear s ‐butyl and t ‐butyl groups. The results are briefly discussed with respect to the atomospheric persistence of the alkenes studied. © 1995 John Wiley & Sons, Inc.