title: Atmospheric lifetimes and fates of selected fragrance materials and volatile model compounds.
abstract: Fragrance materials are semivolatile organic compounds widely used in consumer products. Despite their generally low volatility, it is expected that a fraction of these compounds will volatilize into the atmosphere, where they can photolyze, react with OH radicals, NO3 radicals and O3, and/or undergo wet and dry deposition. Using relative rate methods, rate constants have been measured at 296 +/- 2 K for the gas-phase reactions of OH radicals, NO3 radicals, and 03 with the fragrance materials 1-(1,2,3,4,5,6,7,8-octahydro-2,3,8,8-tetramethyl-2-naphthalenyl)ethanone (OTNE), acetyl cedrene [(3R-(3a,3ab,7b,8aa))-1-(2,3,4,7,8,8a-hexahydro-3,6,8,8-tetramethyl-1H-3a,7-methanoazulen-5-yl)ethan-1-one], and HHCB (1,3,4,6,7,8-hexahydro-4,6,6,7,8,8-hexamethycyclopenta-[gamma]-2-benzopyran) as well as with isochroman which is structurally related to HHCB. Measured rate constants (in cm3 molecule(-1) s(-1) units) are OH radical reactions [OTNE, (9.85 +/- 0.88) x 10(-11); acetyl cedrene, (7.7 +/- 1.6) x 10(-11); HHCB, (2.6 +/- 0.6) x 10(-11); and isochroman, (3.7 +/- 0.6) x 10(-11)], NO3 radical reactions [OTNE, (1.71 +/- 0.19) x 10(-11) and acetyl cedrene, (4.1 +/- 1.0) x 10(-15)], and O3 reactions [OTNE, (2.1 +/- 0.5) x 10(-18) and acetyl cedrene, <2.2 x 10(-18)] where the error limits are two least-squares standard deviations. Rate constants for the OH radical reactions predicted by a structure-reactivity estimation method agree well with the measured values. The dominant tropospheric loss processes for the compounds studied are calculated to be in a reaction with OH radicals during daytime and, for OTNE and acetyl cedrene, with NO3 radicals during nighttime. The calculated atmospheric lifetimes due to daytime reaction with the OH radical are a few hours or less for the fragrance materials studied and indicate that these specific compounds will not undergo long-range transport in the atmosphere.
authors.affiliation: Air Pollution Research Center, University of California, Riverside 92521, USA.
authors.forename: S M
authors.initials: SM
authors.lastname: Aschmann
authors.forename: J
authors.initials: J
authors.lastname: Arey
authors.forename: R
authors.initials: R
authors.lastname: Atkinson
authors.forename: S L
authors.initials: SL
authors.lastname: Simonich
mesh_terms: D000393:Air Pollutants / Q000032:analysis*; D004784:Environmental Monitoring; D006795:Household Products; D017665:Hydroxyl Radical / Q000737:chemistry*; D008962:Models, Theoretical; D009812:Odorants; D009930:Organic Chemicals; D010777:Photochemistry; D014835:Volatilization
chemical_list: D000393:Air Pollutants; D009930:Organic Chemicals; D017665:Hydroxyl Radical