Nitroureas

Adolph and Cichra used a similar strategy of fert-butyl nitrolysis to synthesize 1,5,5-trinitro-l,3-oxazine (95) and the bicycle (96). 

Dagley and co-workers reported the synthesis of 2-nitrimino-5-nitrohexahydro-1,3,5-triazine (100) from the Mannich condensation of nitroguanidine (98), formaldehyde and t-butylamine, followed by nitrolysis of the t-butyl group of the resulting product, 2-nitrimino-5-fert-butylhexahydro-l,3,5-triazine (99). The triazine (100) has also been synthesized from the reaction of nitroguanidine and hexamine in aqueous hydrochloric acid, followed by nitration of the resulting product (97) with a solution of nitric acid in acetic anhydride.  

The Mannich condensation between nitromethane, formaldehyde and t-butylamine, followed by nitrolysis of the resulting product (101), has been used to synthesize 1,3,5-trinitro-hexahydropyrimidine (102) (TNHP) treatment of the latter with formaldehyde in a Henry type methylolation, followed by 0-nitration with nitric acid, yields the nitrate ester (103).  

Chinese chemists reported the base hydrolysis of TNGU. The product, 1,1,2,2-tetranitraminoethane, has been used to prepare a series of heterocyclic nitramines via condensation reactions and may find future use for the synthesis of heterocyclic caged nitramines. 

Li and co-workers recognised the potential of cyclic IV-nitroureas as energetic materials and reported the synthesis of 2,4,6,8-tetranitro-2,4,6,8-tetraazabicyclo[3.3.0]octane-3-one (109) (K-55) from the nitration of 2,4,6,8-tetraazabicyclo[3.3.0]octane-3-one dihydrochloride (108) with absolute nitric acid in acetic anhydride at room temperature the latter obtained from the condensation of lV,lVL(iiformyl-4,5-dihydroxyimidazolidine (107) with urea in aqueous hydrochloric acid. Pagoria and co-workers reported the synthesis of 2,4,6-trinitro-2,4,6,8-tetraazabicyclo[3.3.0]octane-3-one (110) (HK-55) in 72% yield from the nitration of (108) with 90 % nitric acid in acetic anhydride at subambient temperature (Table 5.3). HK-55 has a relatively high density (1.905 g/cm ) coupled with a low sensitivity to shock. 

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NH2-C0-NH NH2,CH5N30. Colourless crystalline substance m.p. 96" C. Prepared by the electrolytic reduction of nitrourea in 20% sulphuric acid at 10 "C. Forms crystalline salts with acids. Reacts with aldehydes and ketones to give semicarbazones. Used for the isolation and identification of aldehydes and ketones. 

Although by our convention the following preparative method is not a nitration, we include it here for the sake of completeness, since it is used in the preparation of Nitraguanidine and Nitrourea... 

If an aqueous solution of nitrourea is boiled, nitrous oxide escapes and the cyanic acid which is produced escapes in part, polymerizes in part, and in part remains in the aqueous liquid where it may react with various substances which may be introduced. If aniline is added to a saturated... 

A fused heterocyclic compound (146) distantly related to the antiinflammatory agent cintazone (Chapter 12), which itself can be viewed as a cyclized derivative of phenylbutazone, retains the activity of the prototype, in the synthesis of 146, reaction of the nitroaniline 139 with phosgene gives intermediate 140, which is then reacted with ammonia to afford the substituted urea (141). Cyclization of the ortho nitrourea function by means of sodium hydroxide leads to the N-oxide (142) this last reaction represents... 

Nitro-3(2,4-dinitrophenyl) urea Nitroguanidine N-Nitromethylamine Nitrourea... 

N-w-heptylurea has been prepared by the action of nitrourea on w-heptylamine.6... 

Nitropropane Nitrosyl fluoride Nitrosyl perchlorate Nitrourea Nitrous acid Nitryl chloride Oxalic acid See under Nitromethane chlorosulfonic acid, oleum Haloalkenes, metals, nonmetals Acetones, amines, diethyl ether, metal salts, organic materials Mercury(II) and silver salts Phosphine, phosphorus trichloride, silver nitrate, semicarbazone Ammonia, sulfur trioxide, tin(IV) bromide and iodide Furfuryl alcohol, silver, mercury, sodium chlorate, sodium chlorite, sodium hypochlorite... 

The nitrile group in 82 has been transformed into other versatile functional groups, and the derivatives so obtained have been used in the synthesis of various naturally occurring C-nucleosides and their analogs. Reduction of 82 with lithium aluminum hydride gave the amine 90 which was, in turn, transformed84 into the ureido and N-ni-troso derivatives (91-93) by treatment with nitrourea, followed by benzylation, and nitrosation.85 The diazo derivative 94, obtained by treatment of 93 with alcoholic potassium hydroxide, was a key intermediate in the synthesis of formycin B and oxoformycin B (see Section III,2,a,b). 

Dithioglyoollic Acid Oxalyl Chloride Nitrourea Nitramide Ethyl Orthoformate Fumaric Acid Glutaric Acid Adipic Acid Pimelic Acid... 

Nitro-3-(2,4-dinitrophenyl)urea, 2705 Nitroguanidine, 0482 iV-Nitromethanimine, 0408 iV-Nitromethylamine, 0478 Nitrourea, 0460... 

There are four important groups of A-nitro compounds which are relevant to energetic materials synthesis. These are primary nitramines, secondary nitramines, secondary nitramides (including A-nitroureas and A, A -dinitroureas) and nitrimines. The synthesis and incorporation of these A-nitro functionalities into organic compounds is the focus of this chapter. 

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. 

The synthesis, properties and potential uses of high performance IV-nitroureas and N,N -dinitroureas are discussed in more detail in Chapter 6. 

Synthesis of nitramines, nitramides and nitroureas via the nitrodesilylation of A/-trimethyisilyl compounds with dinitrogen pentoxide (ref. 122)... 

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