METAL NITRITES

In preparing an aqueous sol ution of a diazonium salt, such as benzene-diazonium chloride, it is usual to dissolve the amine in a slight excess (about 2 2 molecular equivalents) of dilute hydrochloric acid (or alternatively to dissolve the crystalline amine hydrochloride in i 2 equivalents of the acid) and then add an aqueous solution of a metallic nitrite. Nitrous acid is thus generated in situ, and reacts with the amine salt to give the diazonium compound. For a successful preparation of an aqueous solution of the diazonium salt, however, two conditions must always be observed ... 

The Reaction has the following limitations (i) a compound that can liberate nitrous acid in acid solution is required (e.g., a metallic nitrite or a nitroso-amine, p. 204). (2) Nitrophenols and />-substituted phenols do not give the test. (3) Among the dihydroxyphenols. only resorcinol gives a satisfactory positive test. 

Containing a Metal Nitrite Burning Rate Catalyst , USP 3653994 (1972) CA 77, 77448... 

See other metal nitrites, metal oxonon-metallates, oxidants... 

Less stable, more hygroscopic and readily hydrolysed than alkali metal nitrites, it may function as a more powerful oxidant. 

See Ammonium salts (reference 3), also Paper, Sulfur, both above See Other METAL NITRITES, METAL OXONON-METALLATES, OXIDANTS... 

It is probably polymeric and ignites on contact with water. See other nitroso compounds See related METAL NITRITES... 

The reaction of alkyl halides with metal nitrites is one of the most important methods for the preparation of nitroalkanes. As a metal nitrite, silver nitrite (Victor-Meyer reaction), potassium nitrite, or sodium nitrite (Kornblum reaction) have been frequently used. The products are usually a mixture of nitroalkanes and alkyl nitrites, which are readily separated by distillation (Eq. 2.47). The synthesis of nitro compounds by this process is well documented in the reviews, and some typical cases are listed in Table 2.3.92a Primary and secondary alkyl iodides and bromides as well as sulfonate esters give the corresponding nitro compounds in 50-70% yields on treatment with NaN02 in DMF or DMSO. Some of them are described precisely in vol 4 of Organic Synthesis. For example, 1,4-dinitrobutane is prepared in 41 -46% yield by the reaction of 1,4-diiodobutane with silver nitrite in diethyl ether.92b 1-Nitrooctane is prepared by the reaction with silver nitrite in 75-80% yield. The reaction of silver nitrite with secondary halides gives yields of nitroalkanes of about 15%, whereas with tertiary halides the yields are 0-5%.92c Ethyl a-nitrobutyrate is prepared by the reaction of ethyl a-bromobutyrate in 68-75% yield with sodium nitrite in DMF.92d Sodium nitrite is considerably more soluble in DMSO than in DMF as a consequence, with DMSO, much more concentrated solutions can be employed and this makes shorter reaction times possible.926... 

Group 1 nitrates (except lithium nitrate) decompose to give the metal nitrite and oxygen. 

The esters of nitrous acid are characterised by their high velocities of formation and hydrolysis. They are almost instantaneously decomposed by mineral acids and in the method of preparation given this has been taken into account. The slightest excess of hydrochloric acid must be avoided. Advantage is taken of this property of the alkyl nitrites in all cases where it is desired to liberate nitrous acid in organic solvents (in which metallic nitrites are insoluble). Examples addition of N203 to olefines, preparation of solid diazonium salts (p. 286), production of isonitroso-derivatives from ketones by the action of HN02. This synthesis is often also carried out in the manner of the acetoacetic ester synthesis, with ketone, alkyl nitrite, and sodium ethylate the sodium salt of the isonitrosoketone is formed (cf. in this connexion p. 259) ... 

Metal nitrites react with salts of nitrogenous bases to give the corresponding nitrite salts, many of which are unstable. 

METAL OXOHALOGENATES PEROXOACID SALTS METAL NITRITES METAL NITRATES METAL SULFATES METAL AMIDOSULFATES... 

The ter Meer reaction consists of the production of 1,1-dinitro compounds from 1-halo-l-nitroalkanes. The reaction proceeds under the action of alkali metal nitrites in basic medium (Scheme 4.34). 

The synthesis of aliphatic nitro compounds from the reaction of alkyl halides with alkali metal nitrites was discovered by Kornblum and co-workers and is known as the modified Victor Meyer reaction or the Kornblum modification. The choice of solvent in these reactions is crucial when sodium nitrite is used as the nitrite soiuce. Both alkyl halide and nitrite anion must be in solution to react, and the higher the concentration of nitrite anion, the faster the reaction. For this reason, both DMF and DMSO are widely used as solvents, with both able to dissolve appreciable amounts of sodium nitrite. Although sodium nitrite is more soluble in DMSO than DMF the former can react with some halide substrates.Urea is occasionally added to DMF solutions of sodium nitrite to increase the solubility of this salt and hence increase reaction rates. Other alkali metal nitrites can be used in these reactions, like lithium nitrite,which is more soluble in DMF than sodium nitrite but is also less widely available. 

The tautomeric nitronic acids of secondary nitroalkanes or their nitronate salts react with nitrous acid or alkali metal nitrites to yield pseudonitroles.These pseudonitroles are often isolated as their colourless dimers (78b) but are deep blue in monomeric form (78a). Primary nitroalkanes also form pseudonitroles (80b) but these rapidly isomerise to the nitrolic acid (80a).Reactions are commonly conducted by slowly acidifying a mixture containing the nitronate salt and the metal nitrite, during which, the nitronic acid reacts with the nitrite anion. These reactions, first discovered by Meyer, have been used to prepare 2-nitroso-2-nitropropane (78a) and acetonitrolic acid (80a) from 2-nitropropane (76) and nitroethane (22) respectively. ... 

Nitrosation of phenolic substrates usually uses nitrous acid prepared in situ from a dilute mineral acid and an alkali metal nitrite. In general, for every phenolic group present in a substrate an equal number of nitroso groups can be introduced into the aromatic ring phenol, resorcinol and phloroglucinol react with nitrous acid to form 4-nitrosophenol, 2,4-dinitrosoresorcinol and 2,4,6-trinitrosophloroglucinol respectively. 

Metall- nitrit M Oxida- tions- mittel Solvens Temp. C°C] Zeit [h] ... 

However, the production of the />-phenylenediamine [106-50-3] intermediate is more complex, because it involves the diazotization and coupling of aniline [65-53-3]. Aniline reacts with nitrogen oxides, produced via the oxidation of ammonia, to form 1,3-diphenyltriazene [136-35-6] in the process used by Du Pont (208,209) (see Amines, aromatic-aniline and its derivatives). In the Akzo process a metal nitrite salt and acid in water is used (210). The triazene rearranges in the presence of acid and an excess of aniline to form predominately the p-aminoazobenzene [60-09-3] and a small amount of the ortho isomer, 0-aminoazobenzene [2835-58-7]. The mixture of isomers is catalytically reduced to the respective diamines, and they are then separated from the aniline, which is recycled (208,209). The 0-phenylenedi amine [95-54-5] is used in the manufacture of herbicides (see Amines, aromatic-phenylenediamines). 

Divalent and tetravalent Pt probably form as many complexes as any other metal. The platinum(II) complexes are numerous with IV. S, halogens, and C. The letranitritoplatinum complexes are soluble in basic solution. Tetranitntoplatinum(II) ion is formed when a solution of plat-inum(II) chloride is boiled, at about neutral pH, with an excess of NaNO f. The ammonium salt may explode when heated. Generally, platinum-metal nitrites should be destroyed in solution. They never should be heated in the dry form. Pladnum(II) complexes most often have a coordination number of 4. Many compounds have been prepared with olefins, cyanides, nitriles, halides, isonitnles, amines, phosphines, arsines, and nitro compounds. 

It is possible that in the use of alkali metal nitrites for nitrosyl synthesis, the first formed nitrito complex undergoes rapid ligand reduction similar to that above, as in equations (15) and (16). 

The role of radical anions in the detonation of nitroaromatic explosives has been examined.215 The potassium salts of such radicals were formed by mono-, di-, and tri-nitrobenzenes and -toluenes in liquid ammonia solution and, on removal of the solvent, render the material highly susceptible to loss of the metal nitrite, which increases with nitro substitution. Cleavage of the C—N02 M+ bond follows the regioconserved or... 

When nitrates of reactive metals are heated, they decompose to produce the metal nitrite and oxygen gas. 

Potassium K Form the metal nitrite and oxygen is potassium nitrate — potassium nitrite + oxygen ... 

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