Cyclotrimethylenetrinitramine

The name of cyclonite, given to this explosive by Clarence J. Bain because of its cyclic structure and cyclonie nature, is the one by which it is generalIy known in the United States. The Germans calI it Hexogen, the Italian T4.

Properties:
IUPAC NAME: 1,3,5-Trinitroperidro-1,3,5-triazina
OTHER NAME: RDX, Esogeno, Ciclonite, Ciclotrimetilenetrinitrammina MOLECULAR FORMULA: C3H6N6O6 MOLAR MASS: 222.1 g/mol
SHOCK SENSITIVITY: Low
FRICTION SENSITIVITY: Low
EXPLOSIVE VELOCITY: 8,750 m/s

Cyc1onite, prepared by the nitration of hexamethylenetetramine, is derived ultimately from no other raw materiale than coke, air, and water. It has about the same power and brisance as PETN, and a velocity of detonation under the most favorable conditions of about 8500 meters per second. Hexamethylenetetramine, C6H12N4 , is obtained in the form of colorless, odorless, and practicalIy tasteless crystals by the evaporation of an aqueous solution of formaldehyde and ammonia. It is used in medicine under the names of Methenamine, Hexamine, Cystamine, Cystogen, and Urotropine, administered orally as an antiseptic for the urinary tract, and in industry in the manufacture of plastics and as an accelerator for the vulcanization of rubber. It has feebly basic properties and forms a nitrate, C6H12N4 2HNO3, m.p. 165°C, soluble in water, insoluble in alcohol, ether, chloroform, and acetone. The product, C3H6O6N6 , prepared by nitrating this nitrate and patented by Henning for possible use in medicine, was actually cyclonite.
Herz later patented the same substance as an explosive compound, cyclotrimethylenetrinitramine, which he found could be prepared by treating hexamethylenetetramine directly with strong nitric acid. In his process the tetramine was added slowly in small portions at a time to nitric acid (1.52) at a temperature of 20-30°C. When all was in solution, the liquid was warmed to 55°C, allowed to stand for a few minutes, cooled to 20°C, and the product precipitated by the addition of water. The nitration has been studied further by Hale who secured his best yield, 68% in an experiment in which 50 grams of hexamethylenetetramine was added during 15 minutes to 550 grams of 100% nitric acid while the temperature was not allowed to rise above 30°C. The mixture was then cooled to 0°C, held there for 20 minutes, and drawned
[20] .

The formaldehyde which is liberated by the reaction tends to be oxidized by the nitric acid if the mixture is allowed to stand or is warmed. It remains in the spent acid after drowning and interferes with the recovery of nitric acid from it. Cyclonite is a white crystalline solid, m.p. 202°C. It is insoluble in water, alcohol, ether, ethyl acetate, petroleum ether, and carbon tetrachloride, very slightly soluble in hot benzene, and soluble 1 part in about 135 parts of boiling xylene. It is readily soluble in hot aniline, phenol, ethyl benzoate, and nitrobenzene, from alI of which it crystallizes in needles. It is moderately soluble in hot acetone, about 1 part in 8, and is conveniently recrystallized from this solvent from which it is deposited in beautiful, transparent, sparkling prisms. It dissolves very slowly in cold concentrated sulfuric acid, and the solution decomposes on standing. It dissolves readily in warm nitric acid (1.42 or stronger) and separates only partialIy again when the liquid is cooled. The chemical reactions of cyclonite indicate that the cyclotrimethylenetrinitramine formula which Herz suggested for it is probably correct. Cyclonite is hydrolyzed slowly when the finely powdered materiaI is boiled with dilute sulfuric acid or with dilute caustic soda solution.

C3H6O6N6+ 6H2O → 3NH3 + 3CH2O +3HNO3

Quantitative experiments have shown that half of its nitrogen appears as ammonia. If the hydrolysis is carried out in dilute sulfuric acid solution, the formaldehyde is oxidized by the nitric acid and nitrous acid is formed. If cyclonite is dissolved in phenol at 100°C and reduced by means of sodium, it yields methylamine, nitrous acid, and prussic acid. Finely powdered cyclonite, suspended in 80% alcohol and treated with sodium amalgam, yields methylamine, ammonia, nitrous acid, and formaldehyde, a result which probably indicates that both hydrolysis and reduction occur under these conditions. When a large crystal of cyclonite is added to the diphenylamine reagent, a blue color appears slowly on the surface of the crystal. Powdered cyclonite gives within a few seconds a blue color which rapidly becomes more intense. If cinnamic acid is dissolved in concentrated sulfuric acid, and if finely powdered cyclonite is added while the mixture is stirred, gas comes off at a moderate rate, and the mixture, after standing over night and drowning, gives a precipitate which contains a certain amount of p-nitrocinnamic acid.