A bimolecular rate constant,kDHO, of (29 +/- 9) × 10-12 cm3 molecule-1 s-1 was measured using the relative rate technique for the reaction of the hydroxyl radical (OH) with 3,5-dimethyl-1-hexyn-3-ol (DHO, HCCC(OH)(CH3)CH2CH(CH3)2) at (297 +/- 3) K and 1 atm total pressure. To more clearly define DHO's indoor environment degradation mechanism, the products of the DHO + OH reaction were also investigated. The positively identified DHO/OH reaction products were acetone ((CH3)2CO), 3-butyne-2-one (3B2O, HCCC(O)(CH3)), 2-methyl-propanal (2MP, H(O)CCH(CH3)2), 4-methyl-2-pentanone (MIBK, CH3C(O)CH2CH(CH3)2), ethanedial (GLY, HC(O)C(O)H), 2-oxopropanal (MGLY, CH3C(O)C(O)H), and 2,3-butanedione (23BD, CH3C(O)C(O)CH3). The yields of 3B2O and MIBK from the DHO/OH reaction were (8.4 +/- 0.3) and (26 +/- 2)%, respectively. The use of derivatizing agents O-(2,3,4,5,6-pentalfluorobenzyl)hydroxylamine (PFBHA) and N,O-bis(trimethylsilyl)trifluoroacetamide (BSTFA) clearly indicated that several other reaction products were formed. The elucidation of these other reaction products was facilitated by mass spectrometry of the derivatized reaction products coupled with plausible DHO/OH reaction mechanisms based on previously published volatile organic compound/OH gas-phase reaction mechanisms.
J. R. Wells, Exposure Assessment Branch, Health Effects Laboratory Division, National Institute for Occupational Safety and Health, 1095 Willowdale Road, Morgantown, WV 26505