Nitramides hydrolysis

The direct Af-nitration of Ai-alkylamides is the most important of the synthetic routes to secondary nitramides. Hydrolysis of these secondary nitramides is an important but indirect route to primary nitramines, a reaction discussed in Section 5.10. 

Figure 5.71 Synthetic routes to ethylenedinitramine (EDNA) via nitramide hydrolysis...

Although a large number of secondary nitramides have been prepared they have not found wide use as explosives because of their facile hydrolysis to acidic primary nitramines in the presence of water. Research has focused on the synthesis of cyclic and bicyclic A-nitroureas and A, A -dinitroureas because of their high performance. 

Olsen and co-workers used a solution of nitronium tetrafluoroborate in acetonitrile for the V-nitration of acetamides and urethanes at —30°C. The following nitramides were obtained by this method V-nitroacetamide (13 %), V-nitro-2-chloroacetamide (55 %), V-nitro-n-butylacetamide (40 %), V-nitrobenzamide (53 %), ethyl V-nitro-n-butylcarbamate (91 %) and V-nitrosuccinimide (43 %). The low yield of V-nitroacetamide, a primary nitramide, is attributed to competing hydrolysis due to the release of tetrafluoroboric acid as the reaction progresses. The scope of the reaction is improved by moving to more basic solvents like ethyl acetate, 1,4-dioxane and trimethyl phosphate. ... 

The instability of primary nitramines in acidic solution means that the nitration of the parent amine with nitric acid or its mixtures is not a feasible route to these compounds. The hydrolysis of secondary nitramides is probably the single most important route to primary nitramines. Accordingly, primary nitramines are often prepared by an indirect four step route (1) acylation of a primary amine to an amide, (2) A-nitration to a secondary nitramide, (3) hydrolysis or ammonolysis with aqueous base and (4) subsequent acidification to release the free nitramine (Equation 5.17). Substrates used in these reactions include sulfonamides, carbamates (urethanes), ureas and carboxylic acid amides like acetamides and formamides etc. The nitration of amides and related compounds has been discussed in Section 5.5. 

Methylnitramine (1) can be prepared from the hydrolysis of an appropriate secondary nitramide. One route involves the nitration of Ai, Ai -dimethylsulfamide (54) to Ai,Ai -dinitro-iV,iV -dimethylsulfamide (10) with absolute nitric acid, followed by ammonolysis and subse-... 

Bachman and co-workers ° studied the synthesis of the high explosive ethylenedinitrantine (2) (EDNA) from the hydrolysis of secondary nitramides. One of the oldest routes to EDNA (2) involves the nitration of 2-imidazolidone (66) with mixed acid, followed by hydrolysis of the resulting A,A -dinitro-2-imidazolidone (67) with boiling water. 2-Imidazolidone (66) is readily synthesized from the reaction of urea with ethylene glycol, or by treating either... 

W.C.Fernelius, ChemRevs 12, 67(1933) 20,413(1937) 3)Franklin(l935), 54-5 4)Inorg-Synth 1(1939) 74-7 2(1946), 128-35 Nitramide or Nitroxyl amide, 02N.NH2, raw 62.03, N 45.1755. Wh solid, mp 72-5° with de-compn puffs off on rapid heating. Sol in w (slowly dec) and in common solvents, except petr ether. Was first, prepd in 1890 by Mathieu-Plessy but not properly identified. Thiele Lachman prepd it in 1894(Refs 1,2 3) from nitrourethane,OaN.NHCOO.CaHs, and described its props. Since then nitramide was prepd by various investigators, mostly by hydrolysis and decarboxylation of potassium —N —... 

The hydrolysis of nitramide is susceptible to base, but not acid, catalysis. An elevation of pH leads to an increased rate of reaction with no net consumption of base, as is shown in the following reaction ... 

The most numerous cases of homogeneous catalysis are by certain ions or metal coordination compounds in aqueous solution and in biochemistry, where enzymes function catalytically. Many ionic effects are known. The hydronium ion H3O and the hydroxyl ion OH catalyze hydrolyses such as those of esters ferrous ion catalyzes the decomposition of hydrogen peroxide decomposition of nitramide is catalyzed by acetate ion. Other instances are inversion of sucrose by HCl, halogenation of acetone by H and OH , hydration of isobutene by acids, hydrolysis of esters by acids, and others. 

Where the second term in equation (4) is negligible but the water reaction is sufficiently large to be detected, the result is curve d. The important example is the decomposition of nitramide (Brpnsted and Pedersen, 23), and others are the hydrolysis of jS-lactones (Johansson, 29) and the halogenation of nitroparaffins (Pedersen, 30). 

Bransted LFER. Bronsted and Pederson (1923) were the first to describe a relationship between rates and equilibria for a series of compounds. They found that log/cB for base-catalyzed decomposition of nitramide, H2N202, varies linearly with log/CHB+, the acidity constant of the conjugate acid of the catalyst. Rate constants for many other acid- or base-catalyzed reactions (including the hydrolysis of amides, esters, carbamates, and organophosphates, and dissociation of acids and metal-ion complexes) are log-log related to the acid (or base) dissociation constant of the catalyst and follow either of the equations... 

Other examples of the use of populations to refute the contribution of resonance in ground state molecules include the acidity of nitrous and nitric acidio and the rotational surfaces of nitramide O and butadiene.Experimental support for the lack of resonance in amides was reported by Brown and co-workers, who find that the rate of amide hydrolysis correlates with the hybridization on... 

Methods of Preparation. Primary nitramines cannot be prepared by the direct nitration of primary amines. Because of their sensitivity toward acid, they probably do not survive in the strongly acidic environment of the nitration. They are generally made by alkaline hydrolysis of nitramides. 

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