Kinetic studies of OH and O₃ reactions with allyl and isopropenyl acetate

Rate coefficients have been measured for the gas phase reactions of hydroxyl (OH) radicals and ozone with two unsaturated esters, allyl acetate (CH₃C(O)OCH₂CH=CH₂) and isopropenyl acetate (CH₃C(O)OC(CH₃)=CH₂) The OH experiments were carried out using the pulsed laser photolysis - laser induced fluorescence technique over the temperature range 243-372 K and the kinetic data used to derive the following Arrhenius expressions (in units of cm³ molecule^-1 s^-1): allyl acetate, k₁ (2.33 ± 0.27) x 10^-12 exp[(732 ± 34)/T]; and isopropenyl acetate, k₂ (4.52 ± 0.62) x 10^-12 exp[(809 ± 39)/T]. At 298 K, the rate coefficients obtained (in units of 10^-12 cm³ molecule^-1 s^-1) are: k₁ = (27.1 ± 3.0) and k₂ (69.6 ± 9.4). The relative rate technique has been used to determine rate coefficients for the reaction of ozone with the acetates. Using methyl vinyl ketone as the reference compound and a value of 4.8 x 10^-18 cm³ molecule^-1 s^-1 as the rate coefficient for its reaction with O₃, the following rate coefficients were derived at 298 ± 4 K (in units of 10^-18 cm³ molecule^-1 s^-1): allyl acetate, (2.4 ± 4.7) and isopropenyl acetate (0.7 ± 0.2). The results are discussed in terms of structure-activity relationships and used to derive atmospheric lifetimes for the acetates.