Nitroamide

The lithium enolate of AUV-dimethylacetamide underwent addition to 2-aryl-1-nitroethenes to give /faryl-y-nitroamides. The lithium dianions and the trianions of /l-oxo esters and /i,y-dioxo esters undergo addition to 2-aryl-1-nitroethenes to give bicyclic compounds as a single dia-stereomer8. 

Both hyponitrous acid and nitroamide (also known as nitramide) have the formula H2N202. Draw the structures for these molecules and explain any difference in acid-base properties. 

Af-Nitroamides 368 are produced by the rapid rearrangement of the imidoyl nitrates 367 formed in the reactions of imidoyl chlorides with silver nitrate. The transient nitrate esters were detected by NMR spectroscopy411. 

Owing to their importance in toxicology and as carcinogens, nitroamides must be considered seriously. The study of several N-nitroso-N-acetyl amino acids has been reported... 

NNH2,CH3N303 mw 105.06 N 39.98% OB to C02 —7.61% colorl platelets (from ethanol plus eth) mp 158.4—.8° (decompn). Freely sol in acet, acetic acid and ethanol sol in hot w (forms cyanic acid and nitroamide) si sol in benz, chlf and petr eth. CA Registry No [556-89-8]. Prepn is by dehydration of Urea Nitrate with coned sulfuric acid. The compd can be detonated but is not sensitive to percussion or heating (Ref 7)... 

Williams225 has recently reported the synthesis of etherimides by treating halogeno- or nitroamides (152) with alkali metal phenoxides (153) in a nonpolar organic solvent in the presence of a phase transfer catalyst. 

Nitroamide, the simplest of the nitroamines, is formed by the action of dilute acid on potassium nitrocarbamate, which itself results from the nitration of urethane and the subsequent hydrolysis of the nitro ester by means of alcoholic potassium hydroxide. 

Nitroamide is strongly acidic, a white crystalline substance, melting at 72-73° with decomposition, readily soluble in water, alcohol, and ether, and insoluble in petroleum ether. It explodes on contact with concentrated sulfuric acid. The pure material decomposes slowly on standing, forming nitrous oxide and water it cannot be preserved for more than a few days. When an aqueous solution of nitroamide is warmed, gas bubbles begin to... 

The solution which results when ammonium nitrate is dissolved in a large excess of concentrated sulfuric acid evidently contains nitroamide.1 If the solution is warmed directly, no nitric acid distils from it but at about 150° it gives off nitrous oxide which corresponds to the dehydration of the nitroamide by the action of the strong acid. The nitroamide moreover, by the action of the same acid, may be hydrated to yield nitric acid, slowly if the solution is digested at 90° to 120°, under which conditions the nitric acid distils out, and rapidly at ordinary temperature in the nitrometer where mercury is present which reacts with the nitric acid as fast as it is formed. 

Solutions of nitrourea and nitroguanidine in concentrated sulfuric acid contain actual nitroamide, and these substances give up their nitro group nitrogen in the nitrometer. Nitroamide has been isolated 2 both from an aqueous solution of nitrourea and from a solution of the same substance in concentrated sulfuric acid. 

The reaction is reversible, for nitroamide in aqueous solution combines with cyanic acid to form nitrourea. 

In water and in. hydrophilic solvents nitrourea dearranges rapidly into cyanic acid and nitroamide. Alkalis promote the reaction. If an aqueous solution of nitrourea is warmed, bubbles of nitrous oxide begin to come off at about 60°. If it is allowed to stand over night at room temperature, the nitrourea disappears completely and the liquid is found to be a solution of cyanic acid. Indeed, nitrourea is equivalent to cyanic acid for purposes of synthesis. It reacts with alcohols to form carbamic esters (urethanes) and with primary and second amines to form mono-and unsym-di-substituted ureas. 

A freshly prepared solution of nitroguanidine in concentrated sulfuric acid contains no nitric acid, for none can be distilled out of it, but it is ready to produce nitric acid (by the hydration of the nitroamide) if some material is present which will react with it. Thus, it gives up its nitro group quantitatively in the nitrometer, and it is a reagent for the nitration of such substances as aniline, phenol, acet-p-toluide, and cinnamic acid which are conveniently nitrated in sulfuric acid solution. 

A strategy for producing unsymmetrical TB derivatives is based on the Wilcox synthetic protocol (Scheme 5). The reaction of aniline 4 with the derivative of isatoic anhydride, 3,l-benzoxazine-2,4(l//)-dione 5, or 2-nitrobenzoic acid 6 affords ami-noamide 7 and nitroamide 8, respectively. The reduction of 7 or 8 followed by a final cyclization reaction of bisamine 9 yields unsymmetrical TB derivatives 10 (90JOC363). 

The A-nitroimidazolcs are stable for a time even in the presence of water, but treatment with concentrated sulfuric acid cleaves the N-nitro group, and strong base opens the ring. Much of the interest in such compounds is related to their multistep complex substitution reactions in which sequential nucleophilic addition of arylamines, ring opening, ring closure, nitroamide elimination, and rearomatization gives l-aryl-4-nitroimidazoles, e.g., 840 839. This method can also be used to prepare isotopically labeled imidazoles when labeled amino acids are used as the amine. 

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