RATE CONSTANTS FOR THE GAS-PHASE REACTIONS OF OZONE WITH UNSATURATED ALCOHOLS, ESTERS, AND CARBONYLS

The kinetics of the gas-phase reaction of ozone with unsaturated alcoh ols, carbonyls, and esters in air have been investigated at atmospheri c pressure, ambient temperature (285-295 K), and in the presence of su fficient cyclohexane to scavenge the hydroxyl radical which forms as a product of the ozone-unsaturated compound reaction. The reaction rate constants, in units of 10-18 cm3 molecule-1 s-1, are 0.26 +/- 0.05 fo r acrolein, 1.07 +/- 0.05 for 2-ethyl acrolein, 6.0 +/- 0.4 for ethyl vinyl ketone, 4.9 +/- 0.4 for 3-buten-1-ol, 14.4 +/- 2.0 for allyl alc ohol, 105 +/- 7 for cis-3-hexen-1-ol, 7.5 +/- 0.9 for methyl methacryl ate, 2.9 +/- 0.3 for vinyl acetate, 4.4 +/- 0.3 for methyl crotonate, and 8.1 +/- 0.3 for the 1,1-disubstituted alkene 2-ethyl-1-butene. Sub stituent effects on reactivity are discussed by comparison with alkene s and indicate that the reactivity of unsaturated alcohols is the same as that of alkene structural homologues and that the -C(O)OR, -C(O)R, and -CHO groups decrease the reactivity towards ozone as compared to alkyl groups. Estimates are made of the atmospheric persistence of the se unsaturated compounds using the kinetic data obtained in this study as input to structure-reactivity and linear free-energy relationships . (C) 1993 John Wiley & Sons, Inc.