Nitroso compounds with hydrogen peroxide

The conversion of an amino group into a nitro group can be useful when specific substitution patterns are required. The synthesis of 1,4-dinitrobenzene from 4-nitroaniline is illustrative (Scheme 7.5). Oxidation can be accomplished directly using peroxytrifluoroacetic acid or in two steps using H2SO5 (monoperoxysulfuric acid) and oxidation of the resulting nitroso compound with hydrogen peroxide. Alternatively, the amine can be diazotized in fluoroboric acid and then reacted with sodium nitrite in the presence of copper powder. 

Nitrated fluoro compounds are synthesized by electrophilic (NOz+), radical (NO2 ), or nucleophilic (NO2-) methods Indirect nitration routes can suppress the side reactions associated with severe reaction conditions and some nitration reagents Novel fluoronitro compounds, unobtainable by direct nitration, can also be pre pared For example, the nitration of (2-fluoro-2,2-dinitroethoxy)acetaldoxime followed by oxidation of the nitroso intermediate with hydrogen peroxide yields 2-fluoro-2,2-dinitioethyl 2,2-dinitroethyl ether [f] (equation 1)... 

High yields of diacylamines can be easily obtained from imino-chlorides and acids by Mumm-Hesse rearrangement . Certain aromatic amines can be conveniently oxidized to nitroso and nitro compounds with hydrogen peroxide . A facile synthesis of amidi-nium salts has been reported . 

Acyl nitroso compounds (3, Scheme 7.2) contain a nitroso group (-N=0) directly attached to a carbonyl carbon. Oxidation of an N-acyl hydroxylamine derivative provides the most direct method for the preparation of acyl C-nitroso compounds [10]. Treatment of hydroxamic acids, N-hydroxy carbamates or N-hydroxyureas with sodium periodate or tetra-alkyl ammonium periodate salts results in the formation of the corresponding acyl nitroso species (Scheme 7.2) [11-14]. Other oxidants including the Dess-Martin periodinane and both ruthenium (II) and iridium (I) based species efficiently convert N-acyl hydroxylamines to the corresponding acyl nitroso compounds [15-18]. The Swern oxidation also provides a useful alternative procedure for the oxidative preparation of acyl nitroso species [19]. Horseradish peroxidase (HRP) catalyzed oxidation of N-hydroxyurea with hydrogen peroxide forms an acyl nitroso species, which can be trapped with 1, 3-cyclohexanone, giving evidence of the formation of these species with enzymatic oxidants [20]. 

Instead of the peracetic acid oxidation just described, performic acid (prepared from 98 % formic acid and 90% hydrogen peroxide) may also be used as an oxidizing agent for the preparation of nitroso compounds. With this reagent, pentafluoronitrosobenzene and 4-nitrosotetrafluorobromobenzene have been prepared from the respective amines [85]. 

Oxidation of arylamines, nitroso compounds, and azobenzenes. Several 2,6-di-haloanllines have been oxidized successfully to the nitroso compounds with 30% hydrogen peroxide in acetic acid at room temperature. When a solution of the reactants is let stand for a time, crystals of the (dimeric) nitroso compound begin to... 

Oxidation and hydrolysis of nitroso compound 5, readily available from the addition of nitrosyl fluoride to perfluoro(2-methylprop-2-enoyl) fluoride, leads to the corresponding alcohol 6,7 Alternatively, double bonds arc hydroborated and subsequently treated with hydrogen peroxide to yield the alcohol, c. g. conversion of compound 7 into the e.vo-product 8 (exoiendo 86 14).8... 

Ruthenium and iridium catalysts have also been shown to promote the reaction of nitroso compounds with simple ene substrates. In this example, hydrogen peroxide acted as the oxidant to convert the hydroxylamine into the nitroso compound in situ. Ru- or Ir-catalyzed reaction with 2-Me-2-butene (85) then provides a mixture of regioisomers. The metal utilized greatly influences the ratio of products Ru was proven to be more twix selective giving an 8 1 ratio of 156 and 157. ... 

The yield for this method is claimed to be 89 percent. A proposed method for the production of type A RDX consists of oxidizing the compound 1,3,5-trinitrosol, 3,5-triazacyclohexane, which is obtained from hexamethylenetetramine, HCL, and NaN02. Oxidization with hydrogen peroxide and nitric acid yields as an intermediate 1-nitroso-3,5 dinitroso-1,3,5... 

Nitroso compounds are formed selectively via the oxidation of a primary aromatic amine with Caro s acid [7722-86-3] (H2SO ) or Oxone (Du Pont trademark) monopersulfate compound (2KHSO KHSO K SO aniline black [13007-86-8] is obtained if the oxidation is carried out with salts of persulfiiric acid (31). Oxidation of aromatic amines to nitro compounds can be carried out with peroxytrifluoroacetic acid (32). Hydrogen peroxide with acetonitrile converts aniline in a methanol solution to azoxybenzene [495-48-7] (33), perborate in glacial acetic acid yields azobenzene [103-33-3] (34). 

With concentrated mineral acids azobenzene gives red salts, as may be shown by pouring hydrochloric acid on it. Addition of hydrogen leads to the re-formation of the hydrazo-compound. Oxygen is added on and the azoxy-compound formed by the action of hydrogen peroxide or nitric acid. The synthesis of asymmetrical aromatic azo-compounds from nitroso-compounds and primary amines was discussed above. 

The reagent prepared from the reaction of 30 % hydrogen peroxide with glacial acetic acid also contains peroxyacetic acid but the main product of arylamine oxidation is usually the corresponding nitroso compound. On heating with an excess of this reagent the nitro compound is usually obtained. ... 

The most important synthetic methods involve condensation of hydrazine, hydroxylamine or hydrogen peroxide with a 1,4-oxygenated carbon chain, and these procedures are particularly useful for the preparation of pyridazines and 1,2-oxazines. Other methods include Diels-Alder reactions of a diene with an azo or nitroso compound. 

The preparation of nitrosobenzene by oxidation of phenylhydroxylamine with dichromate-sulfuric acid has been described by Gattermann and Wieland.la 2,6-Dihaloanilines can be oxidized to nitroso compounds in good yield by a mixture of 30% hydrogen peroxide and glacial acetic acid.205 Nitroso compounds are also obtained in good yield by oxidation of aryl-hydroxylamines with diethyl azodicarboxylate.206... 

Secondary nitroaUcanes are oxidized to ketones by 3-chloro- or 4-nitrobenzoyl peroxide by way of their anions thus MePhCHN02 gives acetophenone in 92% yield. The same reaction can be carried out with sodium chlorite in methylene chloride/aqueous sodium hydroxide/tetrabutylammonium hydrogen sulphate under phase-transfer conditions. Nitrones 382 (R = H or Me = Me, C02Me, CONHMe or CONMe2 R = t-Bu or Ph) are formed when the sodium salts 381 of nitroaUcanes are treated with the appropriate nitroso compounds 24 ... 

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