Experimental and theoretical understanding of the gas phase oxidation of atmospheric amides with OH radicals: Kinetics, products, and mechanisms

Abstract

Atmospheric amides have primary and secondary sources and are present in ambient air at low pptv levels. To better assess the fate of amides in the atmosphere, the room temperature (298 ± 3 K) rate coefficients of five different amides with OH radicals were determined in a 1 m3 smog chamber using online proton-transfer-reaction mass spectrometry (PTR-MS). Formamide, the simplest amide, has a rate coefficient of (4.44 ± 0.46) × 10-12 cm3 molec-1 s-1 against OH, translating to an atmospheric lifetime of ∼1 day. N-methylformamide, N-methylacetamide and propanamide, alkyl versions of formamide, have rate coefficients of (10.1 ± 0.6) × 10-12, (5.42 ± 0.19) × 10-12, and (1.78 ± 0.43) × 10-12 cm3 m..