Atmospheric Chemistry of Isopropyl Methyl Methylphosphonate and Dimethyl N,N-Dimethylphosphoroamidate
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- 作者：Sara M. Aschmann ; Ernesto C. Tuazon ; William D. Long ; Roger Atkinson
- 刊名：Journal of Physical Chemistry A
- 出版年：2010
- 出版时间：March 18, 2010
- 年：2010
- 卷：114
- 期：10
- 页码：3523-3532
- 全文大小：269K
- 年卷期：v.114,no.10(March 18, 2010)
- ISSN：1520-5215
文摘
Rate constants for the reactions of OH radicals with isopropyl methyl methylphosphonate [(CH3)2CHOP(O)(CH3)OCH3; IMMP] and dimethyl N,N-dimethylphosphoroamidate [(CH3O)2P(O)N(CH3)2; DMDMPA] have been measured over the temperature range 283−350 K and atmospheric pressure of air using a relative rate method. The rate expressions obtained were 2.72 × 10−13 e(1642±144)/T cm3 molecule−1 s−1 (6.72 × 10−11 cm3 molecule−1 s−1 at 298 K) for OH + IMMP and 6.05 × 10−13 e(1185±144)/T cm3 molecule−1 s−1 (3.23 × 10−11 cm3 molecule−1 s−1 at 298 K) for OH + DMDMPA. In addition, rate constants for the reactions of NO3 radicals and O3 with IMMP were measured at 296 ± 2 K, of (4.8 ± 2.1) × 10−16 and <7 × 10−20 cm3 molecule−1 s−1, respectively. Products of the OH radical-initiated reactions were investigated using gas chromatography, in situ atmospheric pressure ionization mass spectrometry (API-MS), and in situ Fourier transform infrared (FT-IR) spectroscopy. For the OH + IMMP reaction, the major initial products appear to be CH3OP(O)(CH3)OC(O)CH3 + •CH3, with subsequent reactions of the methyl radical in the presence of NOx leading to HCHO, CH3ONO, and CH3ONO2. For the OH + DMDMPA reaction, (CH3O)2P(O)N(CH3)CHO was observed as a significant product. Possible reaction mechanisms are discussed.