Atmospheric chemistry of CF3CHCH2 and C4F9CHCH2:: Products of the gas-phase reactions with Cl atoms and OH radicals
Atmospheric chemistry of CF3CHCH2 and C4F9CHCH2:: Products of the gas-phase reactions with Cl atoms and OH radicals
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DOI：
10.1021/jp066736l
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发表时间：
2007-02-08
影响因子：
2.9
通讯作者：
Wallington, T. J.
中科院分区：
文献类型：
--
作者：
Nakayama, T.;Takahashi, K.;Wallington, T. J.
用FTIR烟雾室技术研究了296 K时，在700 Torr的N2/O2稀释剂中，Cl原子和OH自由基引发CF 3CHCH 2氧化的产物。Cl原子引发的CF 3CHCH 2在700 Torr空气中在不存在NOx的情况下的氧化分别以70 +/-5%和6.2 +/-0.5%的产率得到CF 3C（O）CH 2Cl和CF 3CHO。与Cl原子的反应通过加成到> CC <双键（74 +/- 4%到末端和26 +/- 4%到中心碳原子）进行，并导致形成CF 3CH（O）CH 2Cl和CF 3CHClCH 2 O自由基。CF_3CH（O）CH_2Cl自由基的损失机理为与O-2的反应和C-C键断裂的分解，k（O_2）/k（diss）=（3.8 +/-1.8）× 10 ~（-18）cm ~（3）分子（-1）。CF_3CHClCH_2O自由基在大气中的最终归宿是与O-2反应生成CF_3CHClCHO。在NOx存在下，在700 Torr的空气中，OH自由基引发的CxF 2x +1CHCH 2（x = 1和4）的氧化以88 +/-9%的产率产生CxF 2x +1CHO。与OH自由基的反应通过加成到> CC <双键上进行，导致形成CxF 2x +1C（O）HCH 2 OH和CxF 2x +1CHOHCH 2 O自由基。通过C-C键断裂的分解是CxF 2x +1CH（O）CH 2 OH和CxF 2x +1CH（OH）CH 2 O自由基的唯一命运。作为这项工作的一部分，测定了k（Cl+ CF 3C（O）CH 2Cl）=（5.63 +/- 0.66）× 10（-14）cm（3）molecule（-1）s（-1）的速率常数。结果进行了讨论，相对于以前的文献数据和CxF 2x +1CHCH 2的大气氧化的可能性，有助于所观察到的负担的全氟羧酸，CxF 2x +1COOH，在偏远地区。
FTIR-smog chamber techniques were used to study the products of the Cl atom and OH radical initiated oxidation of CF3CHCH2 in 700 Torr of N-2/O-2, diluent at 296 K. The Cl atom initiated oxidation of CF3CHCH2 in 700 Torr of air in the absence of NOx gives CF3C(O)CH2Cl and CF3CHO in yields of 70 +/- 5% and 6.2 +/- 0.5%, respectively. Reaction with Cl atoms proceeds via addition to the > CC < double bond (74 +/- 4% to the terminal and 26 +/- 4% to the central carbon atom) and leads to the formation of CF3CH(O)CH2Cl and CF3CHClCH2O radicals. Reaction with O-2 and decomposition via C-C bond scission are competing loss mechanisms for CF3CH(O)CH2Cl radicals, k(O2)/k(diss) = (3.8 +/- 1.8) x 10(-18) cm(3) molecule(-1). The atmospheric fate of CF3CHClCH2O radicals is reaction with O-2 to give CF3CHClCHO. The OH radical initiated oxidation of CxF2x+1CHCH2 (x = 1 and 4) in 700 Torr of air in the presence of NOx gives CxF2x+1CHO in a yield of 88 +/- 9%. Reaction with OH radicals proceeds via addition to the > CC < double bond leading to the formation of CxF2x+1C(O)HCH2OH and CxF2x+1CHOHCH2O radicals. Decomposition via C-C bond scission is the sole fate of CxF2x+1CH(O)CH2OH and CxF2x+1CH(OH)CH2O radicals. As part of this work a rate constant of k(Cl+CF3C(O)CH2Cl) = (5.63 +/- 0.66) x 10(-14) cm(3) molecule(-1) s(-1) was determined. The results are discussed with respect to previous literature data and the possibility that the atmospheric oxidation of CxF2x+1CHCH2 contributes to the observed burden of perfluorocarboxylic acids, CxF2x+1COOH, in remote locations.