title: Atmospheric chemistry of HFE-7500 [n-C3F7CF(OC2H5)CF(CF3)2]: reaction with OH radicals and Cl atoms and atmospheric fate of n-C3F7CF(OCHO*)CF(CF3)2 and n-C3F7CF(OCH2CH2O*)CF(CF3)2 radicals.
abstract: Relative rate techniques were used to measure k(OH + HFE-7500) = (2.6+/-0.6) x 10(-14), k(Cl + HFE-7500) = (2.3+/-0.7) x 10(-12), k[Cl + n-C3F7CF(OC(O)H)CF(CF3)2] = (9.7+/-1.4) x 10(-15), and k[Cl + n-C3F7CF(OC(O)CH3)CF(CF3)2] < 6 x 10(-17) cm3 molecule(-1) s(-1) at 295 K [HFE-7500 = n-C3F7-CF(OC2H5)CF(CF3)2]. From the value of k(OH + HFE-7500) an estimate of 2.2 years for the atmospheric lifetime of HFE-7500 is obtained. Two competing loss mechanisms for n-C3F7-CF(OCHO.CH3)CF(CF3)2 radicals were identified in 700 Torr of N2/O2 diluent at 295 K; reaction with O2 and decomposition via C-C bond scission with kO2/k(decomp) = 0.013+/-0.006 Torr(-1). The Cl atom initiated oxidation of HFE-7500 in N2/O2 diluent gives n-C3F7CF(OC(O)CH3)CF(CF3)2 as the major product and n-C3F7CF(OC(O)H)CF(CF3)2 as a minor product. The atmospheric oxidation of HFE-7500 gives n-C3F7-CF(OC(O)CH3)CF(CF3)2 and n-C3F7CF(OC(O)H)CF(CF3)2 as oxidation products. The results are discussed with respect to the atmospheric chemistry and environmental impact of HFE-7500.
authors.affiliation: Department of Molecular Engineering, Kyoto University, Japan.
authors.forename: M
authors.initials: M
authors.lastname: Goto
authors.forename: Y
authors.initials: Y
authors.lastname: Inoue
authors.forename: M
authors.initials: M
authors.lastname: Kawasaki
authors.forename: A G
authors.initials: AG
authors.lastname: Guschin
authors.forename: L T
authors.initials: LT
authors.lastname: Molina
authors.forename: M J
authors.initials: MJ
authors.lastname: Molina
authors.forename: T J
authors.initials: TJ
authors.lastname: Wallington
authors.forename: M D
authors.initials: MD
authors.lastname: Hurley
mesh_terms: D000393:Air Pollutants / Q000032:analysis*; D002713:Chlorine / Q000737:chemistry*; D017402:Chlorofluorocarbons / Q000032:analysis* / Q000737:chemistry*; D004784:Environmental Monitoring; D017665:Hydroxyl Radical / Q000737:chemistry*; D016877:Oxidants / Q000737:chemistry*; D010084:Oxidation-Reduction
chemical_list: D000393:Air Pollutants; D017402:Chlorofluorocarbons; D016877:Oxidants; D017665:Hydroxyl Radical; D002713:Chlorine