Nitrous tetroxide

Solutions of dinitrogen tetroxide (the mixed anhydride of nitric and nitrous acids) in sulphuric acid are nitrating agents ( 4.3.2), and there is no doubt that the effective reagent is the nitronium ion. Its formation has been demonstrated by Raman spectroscopy and by cryoscopy ... 

In an excess of nitric acid, nitrous acid exists essentially as dinitrogen tetroxide which, in anhydrous nitric acid, is almost completely ionised. This is shown by measurements of electrical conductivity, and Raman and infra-red spectroscopy identify the ionic species... 

In mixtures of nitric acid and organic solvents, nitrous acid exists mainly as un-ionised dinitrogen tetroxide. The heterolysis of dinitrogen tetroxide is thus complete in sulphuric acid ( 4 i), considerable in nitric acid, and very small in organic solvents. 

If we consider the effect of nitrous acid upon zeroth-order nitration in organic solvents we must bear in mind that in these circumstances dinitrogen tetroxide is not much ionised, so the measured concentration of nitrous acid gives to a close approximation the concentration of dinitrogen tetroxide. Further, the negligible self-ionisation of nitric acid ensures that the total concentration of nitrate ions is effectively that formed from dinitrogen tetroxide. Consequently as we can see from the equation for the ionisation of dinitrogen tetroxide ( 4.3.1),... 

The catalysed nitration of phenol gives chiefly 0- and />-nitrophenol, (< 0-1% of w-nitrophenol is formed), with small quantities of dinitrated compound and condensed products. The ortho para ratio is very dependent on the conditions of reaction and the concentration of nitrous acid. Thus, in aqueous solution containing sulphuric acid (i 75 mol 1 ) and nitric acid (0-5 mol 1 ), the proportion of oriha-substitution decreases from 73 % to 9 % as the concentration of nitrous acid is varied from o-i mol l i. However, when acetic acid is the solvent the proportion of ortAo-substitution changes from 44 % to 74 % on the introduction of dinitrogen tetroxide (4-5 mol 1 ). 

Oxides of Nhrogen Nitric oxide Nitric oxide Nitrous oxide Nitorgen dioxide Nitrogen tetroxide... 

Dimtrogen tetroxide is the most versatile of the nitrosating reagents and, in addition, it is readily available. The nitro-soamide method of deamination gives far superior yields and much less skeletal isomerization than the nitrous acid method (which is essentially limited to aqueous media), and it leads to a greater retention of optical activity than the triazene method3... 

Nitrogen tetroxide is one of the most insidious gases in terms of human toxicity. Inflammation of the lungs may cause only slight pain or pass unnoticed, but the resulting edema several days later may cause death. lOOppm is dangerous for even a short exposure, and 200 ppm may be fatal (Ref 25). Also see under Nitrous Fumes in this Vol... 

The effect of nitrous acid on nitration in nitromethane and acetic acid is also attributed to the effect of nitrate ions even though the ionisation of the dinitrogen tetroxide is much less in these solvents. As noted above (p. 31), the anticatalytic effect of nitrous acid is not governed by k x = a+6[HN03] at nitrous acid concentrations above 0.1 M. 

In sulphuric acid, nitrous acid has a catalytic effect since dinitrogen tetroxide reacts with sulphuric acid to give nitronium ions according to equilibrium (39)102. 

Nitrogen dioxide, tetroxide and monoxide detonate when they are heated with ammonia. Ammonia combusts in the presence of nitrous oxide. 

Phosphorus pentafluoride Phosphorus pentasulfide Phosphorus pentoxide Phosphorus, red Phosphorus tribromide Phosphorus bichloride Water or steam Air, alcohols, water Formic acid, HF, inorganic bases, metals, oxidants, water Organic materials Potassium, ruthenium tetroxide, sodium, water Acetic acid, aluminum, chromyl dichloride, dimethylsulfoxide, hydroxylamine, lead dioxide, nitric acid, nitrous acid, organic matter, potassium, sodium water... 

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... 

Oxidation of aliphatic nitroso functionality is usually facile but is not widely used in energetic materials synthesis. The following reagents have been used in these conversions oxygen,hydrogen peroxide, nitrous oxide, " dinitrogen tetroxide, ... 

Liquid perchloryl fluoride is a typical nonpolar solvent. Most inorganic and organic salts are insoluble in it. Conversely, most covalent, essentially nonpolar substances, boiling within about 50°G of perchloryl fluoride, are completely miscible, e.g., chlorine, boron trifluoride, sulfur hexafluoride, silicon tetrafluoride, phosgene, nitrous oxide, chlorine trifluoride, chlorofluorocarbons, silicon tetrachloride, sulfuryl chloride, dinitrogen tetroxide, and thionyl chloride 106). 

In developing the reactivity scale, Nielsen first investigated the transformation rates of 25 PAHs and four derivatives of anthracene in water-methanol-dioxane solutions, taken as a model of wet particles, and containing small amounts of dinitrogen tetroxide and nitric and nitrous acids. The measured half-lives and relative rates are shown in Table 10.29. The range of reactivities in solution for PAHs of different structures is remarkable, from 100,000 (arbitrarily set) for an-thanthrene (XXXII) to <0.2 for the least reactive compounds ... 

Aminoferrocene (XXXV) can be prepared in low yield by treatment of O-methylhydroxylamine or O-benzylhydroxylamine with ferrocenyllithium (1, 65). Nitroferrocene (XXXVI), unattainable by direct nitration of ferrocene, can be isolated from the reaction of ferrocenyllithium and either n-propyl nitrate or dinitrogen tetroxide at —70° (30, 36). A similar reaction between ferrocenyllithium and nitrous oxide leads to azoferrocene (XXXVII) (08). 

Formation.—When sulphur dioxide is passed into ice-cold fuming nitric acid, crystals of nitrosulphonic. acid separate.1 The acid is also obtained when sulphuric acid is treated with excess of nitrogen peroxide.2 It is also formed by the interaction of sulphur dioxide and nitrogen peroxide both in the absence or presence of water,8 and by the addition in equimolecular proportion of liquid nitrogen tetroxide to chloro-sulphonic acid in the absence of moisture.4 Sulphuric acid acts on either nitrous anhydride or nitrosyl chloride with formation of nitrosulphonic acid, according to the equations ... 

A study of the kinetics of the decomposition of ammonium perchlorate has been made by Bircumshaw and Newman [5]. The gaseous products, up to a temperature of 300°C, were found to be oxygen, chlorine, chlorine dioxide, nitrous oxide, nitrogen tetroxide, chlorine dioxide, hydrochloric acid, perchloric acid and water. The total volume of oxygen and nitrogen produced by unit weight of the solid showed practically no variation up to about 300°C. 

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