Nitrogen HONO formation

With these caveats in mind concerning possible complex formation, we examine potential oxidants for S(IV) in solution. These include 02, 03, H202, free radicals such as OH and H02, and oxides of nitrogen (e.g., NO, N02, HONO, and HN03). Metal catalysis may play a role in some of these reactions. 

Inorganic Reactions. Photooxidation of propylene in the presence of oxides of nitrogen involves numerous inorganic reactions. The role of the NO2 photolysis in initiating O- and Og-reactions has already been discussed. Another inorganic compound of photochemical interest is nitrous acid, HONO, since it provides another source for OH radicals. A reaction scheme for the formation and subsequent photodissociation... 

This reaction is of interest because current models underestimate the production of HONO, which is an important photolytic source of hydroxyl radical (Ammann et al. 1998 Finlayson-Pitts and Pitts 2000). This reaction could also be important as a reductive pathway for nitrogen species in the atmosphere, which is in contrast to most atmospheric reactions which tend to oxidize trace gases (e g., the conversion of SO2 to H2SO4). Molar yields of HONO via Equation (31) (relative to the moles of NO2 lost) typically range from 50 to 100%, while yields of NO are 4 to 30% (Gerecke et al. 1998 Stadler and Rossi 2000). It appears that the formation of NO results from the secondary reaction of HONO at the surface of the soot (Stadler and Rossi 2000). The mechanism of... 

Scheme 9.157. A representation of the reaction of nitrous acid (HONO), via its anhydride, with a generic primary amide (RCONH2), subsequent loss of water (H2O) and nitrogen (N2), and formation of the corresponding carboxylic acid (RCO2H). The reaction is written as second-order in nitrous acid (HONO), although other possibilities may obtain.

The reaction of l-ethyl-3-methyl imidazolium dicyanamide (EmimDCA) with WFNA was followed by IR spectroscopy and the presence of CO2, N2O, H2O and isocyanic acid HNCO was evidenced whereas HCN, HONO, NO and CO do not form (Chowdhury at al. 2009b). The use of labeled nitric acid (HisNOs) leads to the formation of i Ni NO and Ri NCO, proving that the NO fimctionality of nitrous oxide derived from nitric acid and the isocyanic acid nitrogen atom comes from DCA anion only. 

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