β-Ionone reactions with ozone and OH radical:: Rate constants and gas-phase products

The bimolecular rate constants, kappa(OH center dot + beta-ionone) (118 +/- 30) x 10(-12)cm(3) molecule(-1) s(-1) and kO(3+beta-ionone), (0- 19 +/- 0.05) x 10(-16)cm(3) molecule(-1) s(-1), were measured using the relative rate technique for the reaction of the hydroxyl radical (OH) and ozone (O-3) with 4-(2,6,6-trimethyl-1-cyclohexen-1-yl)-3-buten-2-one (beta-ionone) at 297 +/- 3 K and 1 atm total pressure. To more clearly define part of beta-ionone's indoor environment degradation mechanism, the products of the beta-ionone + OH center dot and beta-ionone+O3 reactions were also investigated. The identified beta-ionone+OH center dot reaction products were: glyoxal (ethanedial, HC( = O)C( = O)H), and methylglyoxal (2-oxopropanal, CH3C( = O)C( = O)H) and the identified beta-ionone + O-3 reaction product was 2-oxopropanal. The derivatizing agents O-(2,3,4,5,6-pentafluorobenzyl)hydroxylamine (PFBHA) and N,O-bis(trimethylsilyl)trifluoroacetamide (BSTFA) were used to propose 2,6,6-trimethylcyclohex-1-ene1-carbaldehyde as the other major beta-ionone+OH center dot and beta-ionone+O-3 reaction product. The elucidation of this other reaction product was facilitated by mass spectrometry of the derivatized reaction products coupled with plausible beta-ionone + OH center dot and beta-ionone + O-3 reaction mechanisms based on previously published volatile organic compound + OH center dot and volatile organic compound + 03 gas-phase reaction mechanisms. The additional gas-phase products observed from the beta-ionone+OH center dot reaction are proposed to be the result of cyclization through a radical intermediate. Published by Elsevier Ltd.