Dinitrogen trioxide, decomposition

FIGURE 15.6 Dinitrogen trioxide, N2Oj, condenses to a deep-blue liquid that freezes at 100°C to a pale-blue solid, as shown here. On standing, it turns green as a result of partial decomposition into nitrogen dioxide, a yellow-brown gas. 

During preparation of the IV-nitroso derivative from the lactam in acetic acid solution, the treatment with dinitrogen trioxide must be very effectively cooled to prevent explosive decomposition. 

The reaction in water at pH 7.4 has been much studied since the discovery of the importance of nitric oxide. The products are as for the thermal and photochemical reactions, except that the final product is nitrite ion. This is to be expected since nitric oxide in aerated water at pH 7.4 also yields quantitatively nitrite ion25, by it is believed the series of equations 7-9, which involves oxidation to nitrogen dioxide, further reaction to give dinitrogen trioxide which, in mildly alkaline solution, is hydrolysed to nitrite ion. Under anaerobic conditions it is possible to detect nitric oxide directly from the decomposition of nitrosothiols using a NO-probe electrode system26. Solutions of nitrosothiols both in... 

NIOSH REL (Caprolactam, dust) TWA 1 mg/m3 STEL 3 mg/m (Caprolactam, vapor) TWA 0.22 ppm STEL 0.66 ppm SAFETY PROFILE Moderately toxic by ingestion, skin contact, intraperitoneal, and subcutaneous routes. Human systemic effects by inhalation nose and throat irritation, cough. Experimental reproductive effects. A skin and eye irritant. Potentially explosive reaction with acetic acid + dinitrogen trioxide. When heated to decomposition it emits toxic fumes of NOx. 

SAFETY PROFILE An intense irritant to dssue, skin, and eyes. Flammable by chemical reaction. Ignites or explodes with heat or grinding. Explosive reaction with moisture, chromium trioxide, potassium chlorate, halocarbons (e.g., l,l-diethoxy-2-chloroethane), oxidants, sodium nitrite, air. Can become explosive in storage. Violent reaction with dinitrogen tetraoxide. Will react with water or steam to produce heat and toxic and corrosive fumes of sodium hydroxide and ammonia. When heated to decomposition it emits highly toxic fumes of NH3 and Na20. See also AMIDES. 

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