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May 23, 2013, 8:20am

information and discussion about chemistry of explosives and propellents

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Message:	[quote author=admin board=ac thread=50 post=81 time=1312855621]Explosive derivitives of urea and guanidine are well known, but what about those of biuret and biguanide? Biuret is basically two molecules of urea joined together, NH2C(=O)-NH-C(=O)NH2, while biguanide is basically two molecules of guanidine joined together. NH2C(=NH)-NH-C(=NH)NH2. These two compounds can form nitramines or explosive salts, similar to nitroguanidine or guanidine nitrate. The advantage, of course, is higher density. Almost no information exists about these very uncommon derivitives, which is why they are appearing here. [b]Dinitrobiuret[/b] Biuret has the structure NH2C(=O)NHC(=O)NH2. Nitrobiuret, NO2NHC(=O)NHC(=O)NH2, is prepared by adding biuret in small portions to a mixture of concentrated nitric and sulfuric acids, separates from water as a white, crystalline powder, which melts and decomposes at 165 degrees; it decomposes in boiling water. The potassium and silver salts are anhydrous. Dinitrobiuret, NO2NHC(=O)NHC(=O)NHNO2, produced when the finely divided nitrobiuret is added to fuming nitric acid cooled with a freezing mixture, crystallizes in methanol in white needles, and explodes at 124 degrees, decomposes in boiling water. The potassium salt crystallizes from water in colorless, rhombic plates. The di-nitrate salt of azobisformamidine, NH2C(=NH)N=NC(=NH)NH2, can be prepared by treating aminoguanidine nitrate, with excess dilute nitric acid, with a solution of potassium permanganate. The di-nitrate salt forms yellow plates, which explode at 180-184degC. 2,5-dinitro-azobisformamidine, O2NN=C(NH2)N=NC(NH2)=NNO2, forms redish to orangish-yellow crystals which explode at 165degC. It is obtained by nitrating azobischloroformamidine with 98.8% concentrated nitric acid and acetic anhydride. G.F. wright, Canadian Journal of Chemistry 30, 65-8 (1950). The compound was also prepared by oxidation of 1,6-dinitrobiguanidine with calcium permanganate, obtaining an orange-yellow product, melting point 171-172degC with decomposition. R.A. Henry JACS 75, 958 (1953) Azobischloroformamidine, NH2C(=NCl)N=NC(=NCl)NH2, crystallizes in bright yellow needles or plates, melting at 152degC when crystallized out of water, or 155.5degC from ethyl acetate. The compound has toxicity and explosion hazards. Prepared by reaction of NH2C(=NH)NHNHC(=NH)NH2 with hypochlorite or chlorine gas. Alternatively, aminoguanidine may be oxidized to NH2C(=NH)N=NC(=NH)NH2, then chlorinated with NaOCl, giving a 42% yield of azobischloroformamidine, the product having a 96% purity. [/quote] Expand
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Topic Summary

Posted by Anders Hoveland on Aug 8, 2011, 6:07pm

Explosive derivitives of urea and guanidine are well known, but what about those of biuret and biguanide?
Biuret is basically two molecules of urea joined together,
NH2C(=O)-NH-C(=O)NH2, while biguanide is basically two molecules of guanidine joined together.
NH2C(=NH)-NH-C(=NH)NH2.
These two compounds can form nitramines or explosive salts, similar to nitroguanidine or guanidine nitrate. The advantage, of course, is higher density. Almost no information exists about these very uncommon derivitives, which is why they are appearing here.

Dinitrobiuret
Biuret has the structure NH2C(=O)NHC(=O)NH2. Nitrobiuret, NO2NHC(=O)NHC(=O)NH2, is prepared by adding biuret in small portions to a mixture of concentrated nitric and sulfuric acids, separates from water as a white, crystalline powder, which melts and decomposes at 165 degrees; it decomposes in boiling water. The potassium and silver salts are anhydrous. Dinitrobiuret, NO2NHC(=O)NHC(=O)NHNO2, produced when the finely divided nitrobiuret is added to fuming nitric acid cooled with a freezing mixture, crystallizes in methanol in white needles, and explodes at 124 degrees, decomposes in boiling water. The potassium salt crystallizes from water in colorless, rhombic plates.

The di-nitrate salt of azobisformamidine, NH2C(=NH)N=NC(=NH)NH2, can be prepared by treating aminoguanidine nitrate, with excess dilute nitric acid, with a solution of potassium permanganate. The di-nitrate salt forms yellow plates, which explode at 180-184degC.

2,5-dinitro-azobisformamidine, O2NN=C(NH2)N=NC(NH2)=NNO2, forms redish to orangish-yellow crystals which explode at 165degC. It is obtained by nitrating azobischloroformamidine with 98.8% concentrated nitric acid and acetic anhydride. G.F. wright, Canadian Journal of Chemistry 30, 65-8 (1950). The compound was also prepared by oxidation of 1,6-dinitrobiguanidine with calcium permanganate, obtaining an orange-yellow product, melting point 171-172degC with decomposition. R.A. Henry JACS 75, 958 (1953)

Azobischloroformamidine, NH2C(=NCl)N=NC(=NCl)NH2, crystallizes in bright yellow needles or plates, melting at 152degC when crystallized out of water, or 155.5degC from ethyl acetate. The compound has toxicity and explosion hazards. Prepared by reaction of NH2C(=NH)NHNHC(=NH)NH2 with hypochlorite or chlorine gas. Alternatively, aminoguanidine may be oxidized to NH2C(=NH)N=NC(=NH)NH2, then chlorinated with NaOCl, giving a 42% yield of azobischloroformamidine, the product having a 96% purity.

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