Silver nitrite

Silver nitrite gives a mixture of ethyl nitrite and nitro ethane (p. 131). 

Since aliphatic hydrocarbons (unlike aromatic hydrocarbons, p. 155) can be directly nitrated only under very special conditions, indirect methods are usually employed for the preparation of compounds such as nitroethane, CjHsNO. When ethyl iodide is heated with silver nitrite, two isomeric compounds are formed, and can be easily separated by fractional distillation. The first is the true ester, ethyl nitrite, C,HiONO, of b.p. 17° its identity is shown by the action of hot sodium hydroxide solution, which hydrolyses it, giving ethanol and... 

The iodine atom in iodobenzene (unlike that in the corresponding aliphatic compounds) is very resistant to the action of alkalis, potassium cyanide, silver nitrite, etc. This firm attachment of the iodine atom to the benzene ring is typical of aromatic halides generally, although in suitably substituted nitio-compounds, such as chloro-2,4-dinitrobenzene, the halogen atom does possess an increased reactivity (p. 262). 

Silver nitrite. Warm concentrated solutions of silver nitrate (containing 48 g. of AgNOj) and potassium nitrite (containing 30 g. of KNOj) are mixed, and the mixture is allowed to cool. The silver nitrite which separates is filtered off and washed with water. It may be recrystallised from water at 70°, and is dried either in a vacuum desiccator or in an air oven at about 40° the yield is about 90 per cent. Silver nitrite should be stored in an tightly-stoppered amber bottle. 

Aliphatic nitro compounds. These are isomeric with the alkyl nitrites and may be prepared from the alkyl halide and silver nitrite, for example C,H,aBr + AgNOj — C Hj NO + AgBr... 

In a 200 ml. distilling flask place 64 g. (50 ml.) of dry n-butyl bromide and 80 g. of dry silver nitrite (1). Insert a reflux condenser, carrying a cotton wool (or calcium chloride) guard tube, into the mouth of the flask and close the side arm with a small stopper. Allow the mixture to stand for 2 hours heat on a steam bath for 4 hours (some brown fumes are evolved), followed by 8 hours in an oil bath at 110°. Distil the mixture and collect the fraction of b.p. 149-151° as pure 1-nitro-n-butane (18 g.). A further small quantity may be obtained by distilling the fractions of low boihng point from a Widmer flask. 

The silver nitrite may be prepared as described in Section 11,50, 17. The product supplied by Johnson, Matthey and Co. Ltd., of Hatton Garden, London, E.C. 1, is satisfactory it. should be washed with absolute methyl or ethyl alcohol, followed by sodium-dried ether, and dried in an electrically-heated oven at 100 for 30 minutes (longer heating results in darkening on the surface) the substance should be kept in a vacuum desiccator until required. 

Nitro-n-hexane. Use 41 g. of dry silver nitrite, 51 g. of n-hexyl iodide (35-5 ml.) and 100 ml. of sodium dried ether. Reflux on a water bath for 8 hours decant the ethereal solution and wash the sohd well with sodium dried ether. Distil the residue, after the removal of the ether from the combined extracts, from 5 g. of dry silver nitrite, and collect the fraction of b.p. 190-192° (13 g.) as 1-nitro -hexane. The pure compound is obtained by distilling under diminished pressure b.p. 81 6°/15 mm. 

Nitroethane and 1-(3,4 methylenedioxy) 2- nitropropane This method of producing the above mentioned nitro compounds is by far the best Ritter has come across yet The problem with standard nitroethane synthesis is that the -NO2 source most commonly used is silver nitrite (a la Merck Index citing). Needless to say, this is going to be an expensive compound to make as it is not available commercially but must be synthesized from costly silver nitrate. The other methods mentioned in Vogels 5th masterpiece... 

In the examples, a nitro group is substituted for a hydrogen atom, and water is a by-product. Nitro groups may, however, be substituted for other atoms or groups of atoms. In Victor Meyer reactions which use silver nitrite, the nitro group replaces a hahde atom, eg, I or Br. In a modification of this method, sodium nitrite dissolved in dimethyl formamide or other suitable solvent is used instead of silver nitrite (1). Nitro compounds can also be produced by addition reactions, eg, the reaction of nitric acid or nitrogen dioxide with unsaturated compounds such as olefins or acetylenes. 

Silver Nitrite. Silver nitrite, AgN02, is prepared from silver nitrate and a soluble nitrite, or silver sulfate and barium nitrite. 

Dia2oaminoben2ene has also been prepared by the action of nitrous acid gas on aniline in alcohol by the action of silver nitrite on aniline hydrochloride and together with phenylurea by the action of nitrosophenylurea on aniline in methyl alcohol. Niementowski and Roszkowski have reported studies on the diazotization of aniline, aniline hydrochloride, and aniline sulfate with sodium nitrite and silver nitrite. The procedure described is adapted from that of Fischer. ... 

Replacement of silver nitrite by inexpensive sodiiunor potassium nitrite enhances the imlity of this process Treatment of alkenes v/ith sodiiun nitrite and iodine in ethyl acetate and water in the presence of ethylene glycol gives conjngatednitroalkenesin49-82% yield The method for generation of nitryl iodide is improved by the treatment of iodme v/ith potassium nitrite complexed v/ith 18-crovm-6 in THF under sonicadon, as shovmin Eq 2 32 ... 

In exptl work, indirect methods of introducing nitro groups find wide application as, for example, the replacement of a halogen (iodine or bromine in an alkyl iodide or bromide) by the nitro group, by means of silver nitrite (the Victor Meyer reaction)... 

Sodium nitrite can be used to form nitro compounds with primary or secondary alkyl bromides or iodides, though the method is of limited scope. Silver nitrite gives nitro compounds only when RX is a primary bromide or iodide. Nitrite esters are an important side product in all these cases (10-33) and become the major product (by an SnI mechanism) when secondary or tertiary halides are treated with silver nitrite. 

A kinetic study of the previously reported substitution of aromatic nitro groups by tervalent phosphorus has established an aromatic 5n2 mechanism. Similarities in values of activation energies, and in relative reactivities of phosphite and phosphonite esters, between this displacement and the Arbusov reaction suggest a related mechanism (31), while the lack of reactivity of p-dinitrobenzene is attributed to the need for intramolecular solvation (32). The exclusive formation of ethyl nitrite, rather than other isomers, is confirmed from the decomposition of triethoxy-(ethyl)phosphonium fluoroborate (33) in the presence of silver nitrite. A mechanism involving quinquevalent phosphorus (34) still seems applicable, particularly in view of the recent mechanistic work on the Arbusov reaction. ... 

The synthetic applications of this reagent to the synthesis of nitroalkenes have been known since the 1960s.60 Nitration of alkenes with nitryl iodide, generated in situ from iodine and silver nitrite, is convenient for the synthesis of P-nitrostyrenes with various functional groups.61 This method is applied to the synthesis of ortho-methoxylated phenylisopropylamines, which are potent serotonine agonists (Eq. 2.31).62... 

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... 

Ethyl a-nitrobutyrate may be prepared in 75% yield by the reaction of silver nitrite with ethyl a-iodobutyrate.4 It has been prepared in 18% yield by nitration and subsequent decarboxylation of diethyl ethylmalonate.6 The present method offers the advantage of a direct preparation using sodium nitrite. 

The beginning of aliphatic nitro chemistry goes back to 1872 when V. Meyer and O. Stueber achieved the synthesis of 1-nitropentane by reacting 1-iodopentane with silver nitrite. This report led to an impetus of research in the field, resulting in numerous publications. 

Aromatic cation-radicals can also react with NOj", giving nitro compounds. Such reactions proceed either with a preliminary prepared cation-radical or starting from nncharged componnd if iodine and silver nitrite are added. As for mechanisms, two of them seem feasible—first, single electron transfer from the nitrite ion to a cation-radical and second, nitration of ArH with the NOj radical. This radical is quantitatively formed when iodine oxidizes silver nitrite in carbon tetrachloride (Neelmeyer 1904). 

Nitroethane. 42 g of dry silver nitrite is placed in a flask fitted with a reflux condenser. Note To recover the by-product (ethyl nitrite) ice water must be used in the condenser, which needs to be a long one. Gradually add 34 g of ethyl iodide, so that the mixture does not boil too violently (it should boil vigorously). Do not shake or disturb the flask during this procedure. After the addition, reaction has subsided, warm the flask for 2 hours on a water bath, cool well, and fractionally distill after rigging the apparatus to do so. Ethyl nitrite distills over at 68° and is collected in a below freezing mixture. Nitroethane distills over at 110-114° and must be redistilled once more. Yield 8-9 g. 

A mixture of silver nitrite and iodine reacts with alkenes to give jS-nitroalkyl iodides, and therefore, provides a convenient route to a-nitroalkenes. Treatment of alkenes with ammonium nitrate and trifluoroacetic anhydride in the presence of ammonium bromide, followed by... 

One of the most important reactions for the laboratory synthesis of primary aliphatic nitro compounds was discovered by V. Meyer and O. Stiiber in 1872 and involves treating alkyl halides with a suspension of silver nitrite in anhydrous diethyl ether. Benzene, hexane and petroleum ether have also been used as solvents for these reactions which are usually conducted between 0 °C and room temperature in the absence of light. 

Primary alkyl iodides and bromides are excellent substrates for the Victor Meyer reaction, providing a route to both substituted and unsubstituted nitroalkanes (Table i. i).63,65,70,7i formation of the corresponding nitrite ester is a side-reaction and so the nitroalkane is usually isolated by distillation when possible. The reaction of primary alkyl chlorides with silver nitrite is too slow to be synthetically useful. Secondary alkyl halides and substrates with branching on... 

Synthesis of nitroalkanes and their derivatives from the reaction of alkyl halides with silver nitrite under the Victor Meyer conditions... 

Synthesis of dinitroalkanes from the reaction of dihaloalkanes with silver nitrite and sodium nitrite (ref. 75-79)... 

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