Nitrogen pentoxide

4 NITROGEN PENTOXIDE 3.4.1 Thermal decomposition of N205 (a) Gas phase decomposition of N2Os 

The thermal decomposition of nitrogen pentoxide proceeds according to the stoichiometric equation 

For a steady state in NO and N03, reactions (42), — (42), (30) and (29) give for the experimental first-order rate coefficient (kN20j) for decomposition of pure N205, the expression 

The addition of nitric oxide markedly increases280 the rate of N2Os decomposition. In terms of the accepted mechanism, NO removes NOa in the very rapid reaction (29), thereby preventing reassociation. The stoichiometric equation is now 

In a series of careful investigations, Johnston et al.282 285 have measured the initial rates of the N205 + N0 reaction as a function of temperature and of pressure of various additives. They have successfully interpreted the pressure dependence of the first-order rate coefficient, k42, in terms of the expression 

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The only method utilized commercially is vapor-phase nitration of propane, although methane (70), ethane, and butane also can be nitrated quite readily. The data in Table 5 show the typical distribution of nitroparaffins obtained from the nitration of propane with nitric acid at different temperatures (71). Nitrogen dioxide can be used for nitration, but its low boiling point (21°C) limits its effectiveness, except at increased pressure. Nitrogen pentoxide is a powerful nitrating agent for alkanes however, it is expensive and often gives polynitrated products. 

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. 

At room temperature, Htde reaction occurs between carbon dioxide and sodium, but burning sodium reacts vigorously. Under controUed conditions, sodium formate or oxalate may be obtained (8,16). On impact, sodium is reported to react explosively with soHd carbon dioxide. In addition to the carbide-forrning reaction, carbon monoxide reacts with sodium at 250—340°C to yield sodium carbonyl, (NaCO) (39,40). Above 1100°C, the temperature of the DeviHe process, carbon monoxide and sodium do not react. Sodium reacts with nitrous oxide to form sodium oxide and bums in nitric oxide to form a mixture of nitrite and hyponitrite. At low temperature, Hquid nitrogen pentoxide reacts with sodium to produce nitrogen dioxide and sodium nitrate. 

Nitrates. Anhydrous zirconium tetranitrate [12372-57-5] Zr(N02)4, is prepared from zirconium tetrachloride and nitrogen pentoxide (201). The hydrated compounds are obtained from aqueous nitric acid (165) Zr0(N02)2 2H20 [20213-65-4] is most commonly used Zr(N02)4 5H20 [12372-57-5] can be produced from strong nitric acid. 

The unit of the veloeity eonstant k is see Many reaetions follow first order kineties or pseudo-first order kineties over eertain ranges of experimental eonditions. Examples are the eraeking of butane, many pyrolysis reaetions, the deeomposition of nitrogen pentoxide (NjOj), and the radioaetive disintegration of unstable nuelei. Instead of the veloeity eonstant, a quantity referred to as the half-life iyj is often used. The half-life is the time required for the eoneentration of the reaetant to drop to one-half of its initial value. Substitution of the appropriate numerieal values into Equation 3-33 gives... 

Salpetersaure. /. nitric acid, -anhydrid, n. nitric anhydride, (di)nitrogen pentoxide, nitrogen(V) oxide, -ather, m. nitric ether (ethyl nitrate), -bad, n. nitric acid bath, -dampf, m. nitric acid vapor or fume. 

The Raman spectrum of the monohydrate, HN03.H20, shows it to exist as the hydroxoni-um salt, H30+N03 13. Also, according to analyses of the Raman spectrum, nitric acid exists in aq solns either as a pseudo-acid, N02.0H or as a true acid, N03".H+. In 10 molar aq soln, both acids are present in equal amounts, being caused by the self-dissociation of nitrogen pentoxide (NjOj), while in a 6 molar soln, the pseudo acid is present only to the extent of 2%. and the more dilute the soln, the less pseudo acid is present. In very coned solns, the true acid is present only in small quantities (Refs 32 33)... 

The adjacent charge rule permits resonance of nitrogen pentoxide among the four structures of type A, but exdudes the four structures of type B (as well as the structure with two double... 

With aziridine, nitrogen pentoxide forms a compound that is very unstable and is thought to have the following structure ... 

In the case of relatively simple reaction mechanisms, the net or overall effect of the elementary reactions can be determined by adding them together. For example, the stoichiometric equation for the decomposition of nitrogen pentoxide is... 

Experimental studies of the catalytic decomposition of ozone in the presence of nitrogen pentoxide follow a rate expression of the form... 

Rate constants for the first-order decomposition of nitrogen pentoxide (N2O5) at various temperatures are as follows (Alberty and Silbey, 1992, p. 635) ... 

Scheme 8. Simplified diagram of ICI s technique for the production of nitrogen pentoxide in anhydrous nitric acid [214]...

Nitrogen oxides (NO ), 2 789, 796-797 23 180 27 270. See also Nitric oxide (NO) Nitrogen dioxide (NO2) Nitrogen pentoxide Nitrogen peroxide Nitrogen tetroxide Nitrous oxide (N20) NO entries... 

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