Gas-Phase Reactions of Brominated Diphenyl Ethers with OH Radicals
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- 作者：Jonathan D. Raff ; Ronald A. Hites
- 刊名：Journal of Physical Chemistry A
- 出版年：2006
- 出版时间：September 21, 2006
- 年：2006
- 卷：110
- 期：37
- 页码：10783 - 10792
- 全文大小：136K
- 年卷期：v.110,no.37(September 21, 2006)
- ISSN：1520-5215
文摘
A small volume reaction chamber coupled to a mass spectrometer was used to study the gas-phase kineticsand mechanism of the reaction of OH radicals with diphenyl ether and seven polybrominated diphenyl ethers(PBDEs) with 1-2 bromines. Relative rate constants for these reactions were determined using isopropylnitrite photolysis in He-air mixtures at ~740 Torr between the temperatures of 326-388 K. The Arrheniusexpression for each compound was used to extrapolate the following OH rate constants at 298 K (in units of10-12 cm3 molecule-1 s-1, with 95% confidence intervals): diphenyl ether, 7.45 ± 0.13; 2-bromodiphenylether, 4.7
; 3-bromodiphenyl ether, 4.6
; 4-bromodiphenyl ether, 5.7
; 2,2'-dibromodiphenylether, 1.3
; 2,4-dibromodiphenyl ether, 3.8
; 3,3-dibromodiphenyl ether, 3.2
; and 4,4'-bromodiphenyl ether, 5.1
. The measured OH rate constants are in reasonable agreement with thosepredicted by structure activity relationships. Positive temperature dependences of these OH rate constants areobserved for all compounds measured except for diphenyl ether and 4,4'-dibromodiphenyl ether. Bromophenols(in yields up to 20% relative to the amount of PBDE consumed) and Br2 were characterized as products ofthese reactions, suggesting that OH addition to ipso positions of these brominated aryls may be an importantreaction pathway.
; 3-bromodiphenyl ether, 4.6; 4-bromodiphenyl ether, 5.7; 2,2'-dibromodiphenylether, 1.3; 2,4-dibromodiphenyl ether, 3.8; 3,3-dibromodiphenyl ether, 3.2; and 4,4'-bromodiphenyl ether, 5.1. The measured OH rate constants are in reasonable agreement with thosepredicted by structure activity relationships. Positive temperature dependences of these OH rate constants areobserved for all compounds measured except for diphenyl ether and 4,4'-dibromodiphenyl ether. Bromophenols(in yields up to 20% relative to the amount of PBDE consumed) and Br2 were characterized as products ofthese reactions, suggesting that OH addition to ipso positions of these brominated aryls may be an importantreaction pathway.