Nitrous esters

The existence of an N—N bond in jjrimary nitramines is also proved by the fact that these substances are obtained by the oxidation of diazo compounds. Additional evidence that nitramines contain a nitro and not a nitrite group and hence have a structure different from R—N—ONO is provided by the fact that nitramines are relatively resistant to alkali, whereas nitrous esters are highly unstable. 

Reaction (6) is particularly well suited for use in the preparation of the organic derivatives of hydrazoic acid from the corresponding derivatives of hydrazine. Nitrous esters may be employed, instead of the acid, e.g. ethyl nitrite in the presence of sodium hydroxide... 

Inversion of secondary alcohols. Lattrell and Lohaus reported a few years ago that 3-sulfonyloxy-2-azetidinones react with various nucleophiles with inversion. Thus reaction of trans-i with KN02 in DMSO at 55° results in cis-2 in 77% yield. Presumably an intermediate nitrous ester undergoes hydrolysis under the reaction conditions. Use of potassium formate leads to the same result, hut requires higher temperatures. 

Deoxy-6-nitro derivatives may be prepared analogously, but in lower yields, as a high percentage of nitrous ester is simultaneously formed.147,148 On treatment with base, the glycosidic linkage of 85 is cleaved,146 as indicated in Scheme 12. The further reactions of the unsaturated sulfone 86 have not yet been investigated, but it has been... 

Alkyl Alcohol Nitric ester Nitrous ester Nitro compound... 

Like nitrous esters, alkyl esters of nitric acid enter into reaction with a surplus of Grignard s reagent to form N-dialkylhydroxylamine. 

According to Weinberg [106] in the human system nitroglycerine is reduced to nitrous esters. 

It is necessary to use ethyl nitrite or other alcohol-soluble nitrous ester, instead of sodium nitrite, in order that advantage may be taken of a solvent from which the sodium azide will precipitate out. 

Nitrous esters can react with alkyl peroxides to yield alkyl nitrates [163,221] (see also Vol. II). 

In laboratory methods for the preparation of aliphatic nitro compounds, the V. Meyer reaction [186] consisting in reacting alkyl iodides or bromides with silver nitrite, is widely used. As is well known, the reaction can proceed in two directions, resulting in the formation of a certain quantity of a less stable nitrous ester besides a nitro compound. Instead of silver nitrite mercuric nitrite may be used (Ray [187]). 

The addition of urea to the reacting system prevents side reactions, e.g. the formation of nitrous esters. The yield amounts to about 60%. 

Besides 1,2-dinitroethane a nitrous ester (nitroethyl nitrite) is also formed which is unstable and may decompose. According to N. Levy et al., nitroethyl nitrite may be hydrolysed by dissolving the reaction mixture in methyl alcohol. Dini-troethane then precipitates as a crystalline mass. 

The mechanism of this rearrangement is not clear. We suppose that the intermediate 11 dissociates to give an ion pair 11a. Route b, which involves addition of the N02-anion leads to the nitrous ester 13 which on hydrolysis and elimination of water gives rise to the phenol 14. Route c which involves a [1.2]phenonium rearrangement is favoured in compound 11 a, R2 = PhOMe(4), Table 2 because when R2 is 4-methoxy-phenyl it is a better migrating group than when R2 is phenyl Deprotonation of the cation gives 16. 

McMurrey and co-workers modified the reaction by carrying it out in a reductive medium of TiCI followed by hydrolysis and an oxidizing medium of 0 (92aJ and [92b] respectively. See also Bartlett e/a/. (95). They used /-butyl hydroperoxide in the presence of peniavalent vanadium salt as a catalyst. Korn-blum and Wade (94a) gave an unusual method of oxidation of secondary nitroalkanes 10 ketones with nitrous esters and sodium nitrite at room temperature ... 

Compound 13b was synthesized in four steps via key intermediate 52, in which the configuration of the hydroxyl group at the C-3 position of 50 was inverted. Compound 50 was reacted with trifluoromethanesulfonyl anhydride and pyridine to give triflate 51 (96% yield), which was then reacted with KN02 in the presence of 18-Crown-6, followed by post-treatment of the resulting nitrous ester with water to afford key intermediate 52 (80% yield) [55, 56]. Reduction of the azide moiety of 52 by trimethylphosphine or hydrogenation on Pd on carbon, followed by hydrolysis of the ester moieties gave 13b (48% yield). 

Amongst the impurities to be removed are mixed sulphuric and nitric esters, nitrous esters, nitric esters of sugars, and substances produced by the action of the mixi-il acids on seed husks and on the dried juices in the tubular cotton fibres. Theses au eliminated or rendered harmless by prolonged boiling of the gun-cotton in ktrjgo wooden vats (Fig, 33), the water being changed at intervals. 

Alkyl Alcohols Nitrate esttrs Nitrous esters Nitro groups... 

Fluorinated dienes react vigorously with NO in the liquid and gas phase, and at ambient temperatures [72]. In its reactivity toward NO, hexafluoro-1,3-butadiene may be compared with tetrafluoroethylene. The addition of NO to hexafluoro-1,3-butadiene goes at the two end carbon atoms of the system of conjugated bonds, as a result of which hexafluoro-l,4-dinitro-2-butene and the nitrous ester of hexafluoro-4-nitro-2-buten-l-ol are formed ... 

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