Nitrogen dioxide preparation

T. Johnson and R. Paul, "NAAQS Exposure Model (NEM) and Its Application to Nitrogen Dioxide." Prepared for the U.S. Environmental Protection Agency OAQPS, 1981. 

Nitrogen pentoxide can be made by dehydration of anhydrous nitric acid with phosphorus pentoxide and sublimation from the mixture at about 40°. Resublimation with ozone and more phosphorus pentoxide gives pure white crystals which rattle around in the reaction chamber after slight evacuation. Direct oxidation with ozone of nitrogen dioxide prepared by heating lead nitrate is a somewhat better way of making the material. 

Nitrogen dioxide is prepared by heating the nitrate of a heavy metal, usually that of lead(ll) ... 

Industrially an aqueous solution of chlorine dioxide can be prepared by passing nitrogen dioxide up a packed tower down which sodium chlorate(V) flows ... 

The Kestner-Johnson dissolver is widely used for the preparation of silver nitrate (11). In this process, silver bars are dissolved in 45% nitric acid in a pure oxygen atmosphere. Any nitric oxide, NO, produced is oxidized to nitrogen dioxide, NO2, which in turn reacts with water to form more nitric acid and nitric oxide. The nitric acid is then passed over a bed of granulated silver in the presence of oxygen. Most of the acid reacts. The resulting solution contains silver at ca 840 g/L (12). This solution can be further purified using charcoal (13), alumina (14), and ultraviolet radiation (15). 

Efforts to raise the alpha-selectivity have been made. Thus nitration of anthraquinone using nitrogen dioxide and ozone has been reported (17). l-Amino-4-bromoanthraquinone-2-sulfonic acid (bromamine acid) [116-81 -4] (8) is the most important intermediate for manufacturing reactive and acid dyes. Bromamine acid is manufactured from l-aminoanthraquinone-2-sulfonic acid [83-62-5] (19) by bromination in aqueous medium (18—20), or in concentrated sulfuric acid (21). l-Aminoanthraquinone-2-sulfonic acid is prepared from l-aminoanthraquinone by sulfonation in an inert, high boiling point organic solvent (22), or in oleum with sodium sulfate (23). 

Gaseous nitrogen dioxide is a brown, paramagnetic, non-flammable, toxic, strongly oxidizing, coiTosive substance shipped in approved, low-pressure steel cylinders. It is prepared in situ by heating lead nitrate ... 

Nitrogen dioxide is a toxic gas that can be prepared by the oxidation of NO. 

Another method for the preparation of nitroUc acids was introduced by Ponzio MethylnitroUc acid was prepared by the action of an ether solution of nitrogen dioxide on the isonitrosoacetic acid. The resulting solution is afterwards washed with a little... 

Chlorine dioxide is prepared by passing nitrogen dioxide through sodium chlorate packed in a column ... 

Cyanogen may be prepared by oxidation of hydrogen cyanide with oxygen, nitrogen dioxide, chlorine, or another suitable oxidizing agent, using various... 

Nitrogen dioxide may be prepared by several methods. It is produced when an electric discharge is passed through air. It is made commercially from nitric oxide and air. Nitric oxide made by various processes (See Nitric Oxide) rapidly oxidizes to nitrogen dioxide. It is formed by decomposing nitric acid or by oxidizing ammonia with air ... 

Nitrogen tetroxide always is formed along with nitrogen dioxide during preparation of the dioxide (See Nitrogen Dioxide.) Mixed oxides are produced by oxidation of nitric oxide (NO) in air, heating metal nitrates, or by metals reacting with nitric acids or nitrates. 

In the above preparative method, nitrosyl chloride must be separated from nitric acid otherwise, in the presence of pure and excess nitric acid, it can decompose to nitrogen dioxide and chlorine ... 

Using nitrogen dioxide provides an easier preparation than nitric oxide. 

Selenium dioxide may be prepared by heating selenium with oxygen and nitrogen dioxide. Presence of excess oxygen would oxidize nitrogen dioxide to pentoxide, instead converting selenium dioxide to trioxide ... 

The spontaneous reaction of nitric oxide with thiols is slow at physiological pH and the final product under anaerobic conditions is not a nitrosothiol (Pryor et al., 1982). The reaction is slow because it involves the conjugate base of the thiol (R—S"). At pH 7.0, the oxidation of cysteine by nitric oxide required 6 hr to reach completion and yields RSSR and N 2O as the products. The synthetic preparation of nitrosothiols usually involves the addition of nitrosonium ion from acidified nitrite to the thiol, or oxidation of the thiol with nitrogen dioxide under anaerobic conditions in organic solvents. Nitric oxide will form nitrosothiols by reaction with ferric heme groups, such as found in metmyoglobin or methemoglobin (Wade and Castro, 1990). It is also possible that nitrosyldioxyl radical also reacts with thiols to form a nitrosothiol. 

Similar azo compounds were also prepared by the oxidation of aliphatic hydrazo compounds with nitrogen dioxide [84],... 

Since large amounts of nitric oxide and nitrogen dioxide are generated in the course of the reaction, usually a large excess of nitrogen trioxide has to be employed. This preparation has been carried out either in an ether solution or suspension of the appropriate amide or in a solution of acetic acid containing a small amount of acetic anhydrides to dissolve the amide completely [40a-c],... 

Several patents exist on the use of mixtures of nitrogen dioxide (N02) and nitric oxide (NO) as the reactant for the preparation of Y-nitroso compounds of secondary amines, both in the liquid and in the vapor state, usually in a flow reactor [31,32]. These reactions are not limited to dialkyl amines, as the earlier... 

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