CF3CHFOCH3、CF3CHFOC(O)H和FC(O)OCH3与OH自由基反应的动力学及反应机理

Kinetics and mechanisms of CF3CHFOCH3, CF3CHFOC(O)H, and FC(O)OCH3 reactions with OH radicals.

作者信息

Chen L, Kutsuna S, Tokuhashi K, Sekiya A

机构信息

National Institute of Advanced Industrial Science and Technology (AIST), 16-1 Onogawa, Tsukuba, Ibaraki 305-8569, Japan.

出版信息

J Phys Chem A. 2006 Nov 30;110(47):12845-51. doi: 10.1021/jp064917h.

DOI:10.1021/jp064917h

PMID:17125299

Abstract

The kinetics and mechanism of oxidation of CF3CHFOCH3 was studied using an 11.5-dm3 environmental reaction chamber. OH radicals were produced by UV photolysis of an O3-H2O-He mixture at an initial pressure of 200 Torr in the chamber. The rate constant of the reaction of CF3CHFOCH3 with OH radicals (k1) was determined to be (1.77 +/- 0.69) x 10(-12) exp[(-720 +/- 110)/T] cm3 molecule(-1)(s-1) by means of a relative rate method at 253-328 K. The mechanism of the reaction was investigated by FT-IR spectroscopy at 298 K. CF3CHFOC(O)H, FC(O)OCH3, and COF2 were determined to be the major products. The branching ratio (k1a/k1b) for the reactions CF3CHFOCH3 + OH --> CF3CHFOCH2* + H2O (k1a) and CF3CHFOCH3 + OH --> CF3CF*OCH3 + H2O (k1b) was estimated to be 4.2:1 at 298 K from the yields of CF3CHFOC(O)H, FC(O)OCH3, and COF2. The rate constants of the reactions of CF3CHFOC(O)H (k2) and FC(O)OCH3 (k3) with OH radicals were determined to be (9.14 +/- 2.78) x 10(-13) exp[(-1190 +/- 90)/T] and (2.10 +/- 0.65) x 10(-13) exp[(-630 +/- 90)/T] cm3 molecule(-1)(s-1), respectively, by means of a relative rate method at 253-328 K. The rate constants at 298 K were as follows: k1 = (1.56 +/- 0.06) x 10-13, k2 = (1.67 +/- 0.05) x 10-14, and k3 = (2.53 +/- 0.07) x 10-14 cm3 molecule(-1)(s-1). The tropospheric lifetimes of CF3CHFOCH3, CF3CHFOC(O)H, and FC(O)OCH3 with respect to reaction with OH radicals were estimated to be 0.29, 3.2, and 1.8 years, respectively.

摘要

使用一个11.5立方分米的环境反应室研究了CF3CHFOCH3的氧化动力学和机理。通过在反应室内对初始压力为200托的O3-H2O-He混合物进行紫外光解产生OH自由基。在253 - 328K温度范围内，采用相对速率法测定CF3CHFOCH3与OH自由基反应的速率常数（k1）为(1.77 ± 0.69)×10(-12) exp[(-720 ± 110)/T] 立方厘米·分子(-1)·秒(-1)。在298K下通过傅里叶变换红外光谱研究了该反应的机理。确定CF3CHFOC(O)H、FC(O)OCH3和COF2为主要产物。根据CF3CHFOC(O)H、FC(O)OCH3和COF2的产率，在298K时CF3CHFOCH_{3}+OH→CF3CHFOCH2* + H2O（k1a）和CF3CHFOCH_{3}+OH→CF3CF*OCH3 + H2O（k1b）反应分支比（k1a/k1b）估计为4.2:1。在253 - 328K温度范围内，采用相对速率法测定CF3CHFOC(O)H（k2）和FC(O)OCH3（k3）与OH自由基反应的速率常数分别为(9.14 ± 2.78)×l0(-13) exp[(-1190 ± 90)/T]和(2.10 ± 0.65)×10(-13) exp[(-630 ± 90)/T] 立方厘米·分子(-1)·秒(-1)。298K时的速率常数如下：k1 = (1.56 ± 0.06)×10-13、k2 = (1.67 ± 0.05)×10-14和k3 = (2.53 ± 0.07)×10-14 立方厘米·分子(-1)·秒(-1)。估计CF3CHFOCH3、CF3CHFOC(O)H和FC(O)OCH3与OH自由基反应的对流层寿命分别为0.29年、3.2年和1.8年。