Atmospheric Fate of Nitramines: An Experimental and Theoretical Study of the OH Reactions with CH₃NHNO₂ and (CH₃)₂NNO₂

The rates of CH₃NHNO₂ and (CH₃)₂NNO₂ reaction with OH radicals were determined relative to CH₃OCH₃ and CH₃OH at 298 ± 2 K and 1013 ± 10 hPa in purified air by long path FTIR spectroscopy, and the rate coefficients were determined to be <i>k</i>_{OH+CH₃NHNO₂} = (9.5 ± 1.9) × 10^–13 and <i>k</i>_{OH+(CH₃)₂NNO₂} = (3.5 ± 0.7) × 10^–12 (2σ) cm³ molecule^–1 s^–1. Ozone was found to react very slowly with the two nitramines, <i>k</i>_{O₃+nitramine} < 10^–21 cm³ molecule^–1 s^–1. Product formation in the photo-oxidation of CH₃NHNO₂ and (CH₃)₂NNO₂ was studied by FTIR, PTR-ToF-MS, and quantum chemistry calculations; the major products in the OH-initiated degradation are the corresponding imines, CH₂NH and CH₃NCH₂, and <i>N</i>-nitro amides, CHONHNO₂ and CHON­(CH₃)­NO₂. Atmospheric degradation mechanisms are presented