Oxidations of nitrogen

Nitrogen monoxide is the most stable of all the oxides of nitrogen. It can be prepared in small amounts by direct combination of the... 

With more concentrated nitric acid, oxides of nitrogen are formed. 

Equip a 500 ml. three necked flask with a reflux condenser, a mercury-sealed mechanical stirrer and separator funnel, and support it on a water bath. Attach an absorption device (Fig. II, 8, 1, c) to the top of the condenser (1). Place 134 g. (152 ml.) of A.R, benzene and 127 g. of iodine in the flask, and heat the water bath to about 50° add 92 ml. of fuming nitric acid, sp. gr. 1-50, slowly from the separatory funnel during 30 minutes. Oxides of nitrogen are evolved in quantity. The temperature rises slowly without the application of heat until the mixture boils gently. When all the nitric acid has been introduced, reflux the mixture gently for 15 minutes. If iodine is still present, add more nitric acid to the warm solution until the purple colour (due to iodine) changes to brownish-red. 

It is advisable to add the sodium nitrite solution, particularly in preparations on a larger scale, through a separatory or dropping funnel with the tip of the stem extending well below the sui-face of the liquid tliis will prevent loss of nitrous acid by surface decomposition into oxides of nitrogen. 

Method 1. Place 20 g. of crude benzoin (preceding Section) and 100 ml. of concentrated nitric acid in a 250 ml. round-bottomed flask. Heat on a boiling water bath (in the fume cupboard) with occasional shaking until the evolution of oxides of nitrogen has ceased (about 1 -5 hours). Pour the reaction mixture into 300-400 ml. of cold water contained in a beaker, stir well until the oil crystallises completely as a yellow solid. Filter the crude benzil at the pump, and wash it thoroughly with water to remove the nitric acid. RecrystaUise from alcohol or methylated spirit (about 2-5 ml. per gram). The yield of pure benzil, m.p. 94-96°, is 19 g. 

Dissolve 1.000 g Au in 10 ml of hot HNO3 by dropwise addition of HCI, boil to expel oxides of nitrogen and chlorine, and dilute to volume. Store in amber container away from light. 

Fig. 7. NO formation for the Provo-Orem bus mn at a compression ratio of 12 1 at 30°C, 3000 rpm, where A is brake mean effective pressure B, brake thermal efficiency and C, oxides of nitrogen, (a) Effect of equivalence ratio, ( ), at a water/H2 mass ratio of 6.0 and spark = 17° before top-dead (BTC) and (b), effect of water injection where (j) = 0.60 and spark = 14°BTC. To convert MPa to psi, multiply by 14.

Oxides of nitrogen, NO, can also form. These are generally at low levels and too low an oxidation state to consider water scmbbing. A basic reagent picks up the NO2, but not the lower oxidation states the principal oxide is usually NO, not NO2. Generally, control of NO is achieved by control of the combustion process to minimize NO, ie, avoidance of high temperatures in combination with high oxidant concentrations, and if abatement is required, various approaches specific to NO have been employed. Examples are NH injection and catalytic abatement (43). 

Air Pollution. Particulates and sulfur dioxide emissions from commercial oil shale operations would require proper control technology. Compliance monitoring carried out at the Unocal Parachute Creek Project for respirable particulates, oxides of nitrogen, and sulfur dioxide from 1986 to 1990 indicate a +99% reduction in sulfur emissions at the retort and shale oil upgrading faciUties. No violations for unauthorized air emissions were issued by the U.S. Environmental Protection Agency during this time (62). 

Unpiotonated hydioxylamine is oxidized rapidly by ozone, / = 2.1 X 10 (39). The reaction of ozone with the lower oxides of nitrogen (NO and NO2) is also rapid and quantitative the end product is nitrogen pentoxide, which is also a catalyst for the decomposition of ozone (45). Nitrous oxide, however, reacts slowly (k < 10 ) (39). Nitrogen-containing anions, eg, nitrite and cyanide, also ate oxidized by ozone (39). Nitrite is oxidized to nitrate (fc = 3.7 X 10 and cyanide is oxidized rapidly to cyanate (fc = 2.6 X 10 (46) and 10 -10 (39)). Cyanate, however, is oxidized slowly. 

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