Tetroxides dissociation

Nitrogen tetroxide dissociates completely in anhydrous nitric acid forming NO" and NO ions ... 

Equilibria for the reaction N20g(g) + N0(g) + N02(g) have been studied by Beattie and Bell ( ), Verhoek and Daniels (2), and Abel and Proisl (3). The results of Beattie and Bell are the most extensive, but they depend on the early analysis of Giauque and Kemp (4) for the simultaneous equilbrium N20 (g) 2 N02(g). The JANAF analysis of the tetroxide dissociation has been used to recalculate the data of Beattie and Bell. Non-ideality of N20 and NOg was allowed for by use of the equations of state of Giauque and Kemp, while non-ideality of NO and N20g was removed by extrapolation of the equilibrium constants to zero pressure in a manner similar to that of Beattie and Bell. The data of Verhoek and Daniels and of Abel and Proisl have not been recalculated. 2nd and 3rd... 

This equation can also be used to calculate the effective heat capacity Cv.cff of a gas that is undergoing a chemical reaction, such as nitrogen tetroxide dissociating to form nitrogen dioxide,... 

Cellulose cannot be oxidized in ether-like solvents such as dioxane, diphenyl ether or methyl tertiary butyl ether due to binding of nitrogen tetroxide by the solvent molecules and solvation of tlie reaction centers of cellulose by the solvent (Pavyiuechenko et al, 1975). The rate of the oxidation reaction in inert solvents such as Freon or fluorinated hydrocarbons is controlled in part by the partitioning of the oxidant between the solvent and the cellulose. In Freon 113, an excellent solvent for nitrogen dioxide (Ashton Moser, 1968), the rate of oxidation is slow compared to fluorinated hexane, a poor solvent for the oxidant (Boardman etal, 1993). Reaction rates are also controlled by the polarity of the solvent which affects the dissociation of the nitrogen tetroxide dissociation and rate increase in non-polar solvents. 

Dinitrogen tetroxide dissociates into nitrogen dioxide N204(g) 2N02(g)... 

Other liquid inorganic compounds show the auto-dissociation characteristic of water and liquid ammonia for example, dinitrogen tetroxide (p. 231), as well as undergoing the more familiar homolytic dissociation... 

Dinitrogen tetroxide, N2O4, as a liquid, has some power as a solvent, and appears to dissociate slightly to give nitrosyl nitrate, thus ... 

Tetrasilver tetroxide is a powerful oxidizer for sanitizing swimming pools, hot tubs, and industrial cooling system waters (see Water, treatment of SWIMMINGPOOLS, SPAS, AND HOT tubs). This oxide is slightly soluble and its dissociation into silver ions is enhanced by the addition of the oxidizer KgSgOg. Bivalent and trivalent silver disinfectants have been shown to be from 50 to 200 times more effective as sanitizers than monovalent silver compounds. 

A flask of volume 5.00 L is evacuated and 43.78 g of solid dinitrogen tetroxide, N,Q4, is introduced at — 196°C. The sample is then warmed to 25°C, during which time the N204 vaporizes and some of it dissociates to form brown NO, gas. The pressure slowly increases until it stabilizes at 2.96 atm. 

The brown nitrogen dioxide gas condenses to a yellow liquid which freezes to colourless crystals of dinifrogen tetroxide. Below 150°C the gas consists of molecules of dinifrogen tetroxide and nitrogen dioxide in equilibrium and the proportion of dinifrogen tetroxide increases as the temperature falls. Above 150°C nitrogen dioxide dissociates into nitric oxide and oxygen. 

The irreversible decay of tetroxide occurs as the result of the dissociation of the O—OR bond to produce R03 and RO radicals ... 

The (864) radical is essentially the sulfur tetroxide anion-radical. It is named the snlfate radical because it is formed from the persulfate ion as a result of UV irradiation or heating (at 80-100°C) of persulfate salts M282O8 in aqueous solutions. Under these conditions, 820 -> 2804 dissociation takes place (Minisci et al. 1983, Dias and Vieira 1996). 

When heated in air at 370°C, the trioxide converts to tetroxide, Pb304. It dissociates to lead monoxide on heating at 530°C. It decomposes in acids forming lead dioxide and the corresponding salts of the acids. With concentrated sulfuric acid, the products are lead dioxide and lead sulfate with evolution of... 

While low temperature favors dimeric tetroxide, equilibrium shifts toward dioxide at higher temperatures. Thus, at 100°C the composition of the vapor is 90% NO2 and 10% N2O4. At 140°C, the tetroxide completely dissociates into dioxide. At 150°C, thermal dissociation of dioxide begins, giving NO and O2. Decomposition of NO2 is complete at about 600°C. At 21.15°C, the boding point of N2O4, the hquid composition is 99.9% N2O4 and 0.1% NO2. 

From my estimates on the thermodynamic properties of peroxy and polyoxide molecules and radicals, we can estimate that the bond dissociation energy of the tetroxide is about 5 kcal. Thus, at room temperature, or even at dry ice temperature, the tetroxide is extremely unstable and should redissociate into the more stable (from a thermodynamic point of view) peroxy radicals. The competing step would be a concerted decomposition into an RO and an R03 (Step 14) radical, which would be uphill by 20 kcal., or else a concerted decomposition into 2 RO radicals and 02 (Step 14 ). The latter is almost thermoneutral. If we take the current data at face value, it provides, from the reported activation energy at least, strong evidence that the propagating interaction of two alkylperoxy radicals proceeds in a concerted fashion. 

Considering nitration with the help of N02/N204 in an aprotic medium, one should avoid a simplified approach to its mechanism. Of course, radical dissociation of dinitrogen tetroxide is clear and usual. However, two ionic routes of dissociation of N204 are also possible in aprotic media ... 

Bauer G (2000) Reactive oxygen and nitrogen species efficient, selective and interactive signals during intercellular induction of apoptosis. Anticancer Res 20 4115-4140 Beckwith AU, Davies AG, Davison IGE, Maccoll A, Mruzek MH (1989) The mechanisms of the rearrangements of allylic hydroperoxides 5a-hydroperoxy-3p-hydrocholest-6-ene and 7a-hydro-peroxy-3(1-hydroxycholest-5-ene. J Chem Soc Perkin Trans 2 815-824 Behar D, Czapski G, Rabani J, Dorfman LM, Schwarz HA (1970) The acid dissociation constant and decay kinetics of the perhydroxyl radical. J Phys Chem 74 3209-3213 Benjan EV, Font-Sanchis E, Scaiano JC (2001) Lactone-derived carbon-centered radicals formation and reactivity with oxygen. Org Lett 3 4059-4062 Bennett JE, Summers R (1974) Product studies of the mutual termination reactions of sec- alkylper-oxy radicals Evidence for non-cyclic termination. Can J Chem 52 1377-1379 Bennett JE, Brown DM, Mile B (1970) Studies by electron spin resonance of the reactions of alkyl-peroxy radicals, part 2. Equilibrium between alkylperoxy radicals and tetroxide molecules. Trans Faraday Soc 66 397-405... 

As a simple example of how this relation may be used to establish the equilibrium composition of reacting gases, consider the dissociation of nitrogen tetroxide when its temperature is increased from room temperature to some elevated value. 

The dissociation energy of 0—0 bond in the intermediate tetroxide structure is about 35 kJ/mole. Comparing the stability of tetroxides with respect to peroxides [95] by the value of temperature at which in 1 mol of a corresponding compound at least 1 molecule is dissociated, we receive the value — 200 °C against 30 °C. From this it is obvious that the conception of tetroxides in oxidation mechanisms at ambient and higher temperatures is unconceivable. 

Some dissociation of N2O4 by the light which it absorbs would be expected. It is quite possible that nitrogen tetroxide is dissoci-... 

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