Rate constants and conversion ratios for aqueous‐phase reactions of SO with CnF2n+1C(O)O− (n = 4–7) at 298 K |
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Authors: | Shuzo Kutsuna Kazuhide Koike Hisao Hori |
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Affiliation: | National Institute of Advanced Industrial Science and Technology (AIST), AIST Tsukuba West, 16‐1 Onogawa, Tsukuba, Ibaraki 305‐8569, Japan |
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Abstract: | Kinetic data for aqueous‐phase reactions of sulfate anion radicals (SO ) with perfluorocarboxylates (CnF2n+1C(O)O?) are needed to evaluate removal and transformation processes of CnF2n+1C(O)O? species in the environment, but rate constants for the reactions of SO with CnF2n+1C(O)O? (kn) have been reported only for short‐chain CnF2n+1C(O)O? species (n = 1–3). Since CnF2n+1C(O)O? reacted with SO to form CmF2m+1C(O)O? (m < n), we determined relative rates kn?1/kn for the reactions of SO with CnF2n+1C(O)O? (n = 4–7), along with conversion ratios for conversion of CnF2n+1C(O)O? into Cn?1F2n?1C(O)O? (αn) and into Cn?2F2n?3C(O)O? (βn) at 298 K. SO was photolytically generated from S2O by use of sunlamps (λ ≈ 310 nm). Even if kn and kn?1 change with increasing ionic strength, kn?1/kn can be determined when kn?1/kn and αn remain almost constant during the reaction. The values of kn/k1 for n = 4–7 were nearly equal, and their average was 0.82 ± 0.04 (2σ). Conversion ratios of αn and βn were mostly independent of n for n = 4–7, and their averages were 0.77 ± 0.07 (2σ) and 0.13 ± 0.08, respectively. Branching ratios of reactions of a possible intermediate (CnF2n+1O?), reaction of CnF2n+1O? with H2O, and fission of the C? C bond of CnF2n+1O?, seemed to determine αn and βn. © 2009 Wiley Periodicals, Inc. Int J Chem Kinet 41: 735–747, 2009 |
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