Reciently i've successfully prepared TNGU by nitration of glycouryl. TNGU - colorless or slightly yellowish crystaline compound, insoluble in water and is slowly hydrolized by it to tetranitraminoethane, fast decomposed in alkaline solution. Decomposes by hot ethanol. Very powerfull, and dense explosive, easily pressed, density is 2.02 g/cm3 (from nitromethane), density of technical grade product is 1.98 g/cm3. Slightly more sensitive then PETN, soluble in nitromethane. Decomposition starts slightly above 100C, flash point 200C. Detonation velocity is 9150 m/sec at 1.95 g/cm3. Brisance by sand test is 61.9g of crushed sand (TNT - 48g, PETN - 62.7g). Practitial use is not widespread because of unsufficent hydrolitic stability, partialy decomposed on melt with TNT. Can be used in flegmatized state or with thermoplastic polymeres.

Production of glycouryl. 5.84g of glyoxal (0.1 mol, 12.3 ml 40%, density 1.19 g/cm3) is mixed with 15g of powdered urea, solution is mixed until urea is completely dissolved and then acidified by sulphuric acid to pH~0 and placed on water bath under reflux condenser. Rection mixture is heated on water bath for 1 hour, cooled and filtered to get glycouryl. Crude product is mixed with 100 ml of boiling water, well stirred and mixture is left to cool to room temperature. Pure glycouryl is filtered and dried at room temperature. Yield is 9.9g (71%).

Synthesis of TNGU. 15 ml of ice cold concentrated nitric acid (density 1.51 ~100%) is slowly added drop by drop with stirring to 45 ml of cold acetic anhydride, not allowing temperature to rise above 15C, mixture is left to stand for 30 minutes at room temperature (Note#1). 6g of finely powdered glycouryl is added by portion with stirring, mixture is stirred at 20C for 30 minutes and then heated to 30C for 2 hours (Note#2). Precipitate of TNGU is filtered on glass filter, washed with 75 ml of ice cold water, 50 ml if ice cold ethanol and dried at dessicator over P2O5. Yield is 7.1g (52%).

1. Addition of nitric acid causes slight heating, acid should be added drop by drop with gentle stirring, not allowing temperature to rise above 15C. Acetic anhydride reacts with nitric acid forming acetyl nitrate and N2O5, witch are in equilibrium with each other. Accumulation of this products takes some time. At 20C conversion of acetic anhydride to acetyl nitrate reaches 70%.

2. Additon of glycouryl to acid mixture, produces no or very low heat, but glycouryl must be added by portions to ensure efficient mixing. Glycouryl and product of it's nitration are insoluble in nitrating mixture, so nitration proceeds on the surface of glycouryl particles and precipitate is slowly covered by solid layer of nitration product, blocking acess of acid to inner layers witch can be low nitrated. Because of that all nitration must be carried out with efficent stirring, to ensure complete nitration, not allowing solid layer to settle.