dinitroaniline

     Dinitroaniline is a very stable high explosive similar to TNT. There are several isomers of dinitroaniline, but the most useful and easiest to make is 2,4-dinitroaniline. Dinitroaniline is rarely used alone as an explosive, but rather it is used in compositions with other high explosives, mostly for shells. The Germans used it in WWII along with TNT to make warheads less brisant so bomb fragments would be larger (and hence more lethal), and also to stretch dwindling TNT supplies. While more stable than TNT it has a lower detonation velocity. Dinitroaniline is an intermediate for making dyes, and has also been used as an herbicide. It is quite toxic as well. The primary herbicide use of dinitroaniline is to control weeds. It prevents weeds from germinating and must be worked into the soil when applied. It also kills most varieties of grasses.

CHEMICALS	APPARATUS
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     Synthesis 1: A wide-mouthed 250-cc. flask (Note 1) containing a mixture of 50 g. (0.25 mole) of technical 2,4-dinitrochlorobenzene (Note 2) and 18 g. (0.23 mole) of ammonium acetate is half immersed in an oil bath. The flask is fitted with a reflux condenser and an inlet tube, the lower end of which is at least 2 cm. wide (to prevent clogging) and which nearly touches the surface of the reaction mixture. During the operation ammonia gas is introduced through a bubble counter which contains a small amount of strong potassium hydroxide solution (12 g. of potassium hydroxide in 10 cc. of water). The oil bath is heated to 170° and maintained at that temperature for six hours during which time ammonia gas is passed through at the rate of three to four bubbles per second. After the mixture has cooled, the solid is broken up by means of a glass rod and mixed with 100 cc. of water; the mixture is then heated to boiling and filtered while hot. The residue is dissolved in 500 cc. of boiling alcohol, and water is added (about 150 cc.) until the solution becomes turbid. Heat is applied until the turbidity disappears and then the solution is allowed to cool. After standing overnight, the crystals are filtered and dried. The yield is 31–35 g. (68–76 per cent of the theoretical amount) of 2,4-dinitroaniline, melting at 175–177° (Note 3) and (Note 4). For further purification the product is recrystallized in the same manner from alcohol and water, using 20 cc. of alcohol per gram of solid. Ninety per cent of the crude material is recovered as recrystallized product melting sharply at 180°. 2. Notes 1. The neck of the flask must be large enough to admit the wide inlet tube. A 250-cc. extraction flask is most convenient. 2. The technical dinitrochlorobenzene used had a freezing point of 45°. The higher yield given is obtained using a product once recrystallized from alcohol (m.p. 48°). 3. Some specimens of technical dinitrochlorobenzene used contained undetermined impurities that formed double compounds with the dinitroaniline. These remained in the filtrate. It was not worth the trouble to recover the small amount of amine thus lost. 4. The value of this method is that no autoclave is required. It was not satisfactory when applied to the nitrochlorobenzenes. Synthesis 2: Prepare a solution of 1 g of 2,2,4,4-tetranitrodiphenyl ether in 10 mL of dimethylformamide in a test tube and bubble gaseous ammonia through the solution for 15 minutes while maintaining a temperature of 25 C. The reaction is then poured into a beaker containing 50-75 mL of water. A precipitate of dinitroaniline will form. Allow several minutes for it to fully precipitate and to settle. Collect this material by filtering and allow it to dry. To the liquid filtrate add enough hydrochloric acid to make the solution slightly acidic to precipitate dinitrophenol, which can be collected by filtration and allowed to dry. Yield of dinitroaniline is 85%, yield of dinitrophenol is 65%. An alternative to this process is to use only 0.5 g of 2,2,4,4-tetranitrodiphenyl ether in dimethylformamide and to use 0.28 g of 25% aqueous ammonia instead of gaseous ammonia. The mixture is sealed in a pressure reaction vessel and heated to 100 C for 15 minutes at a pressure of 4 to 5 atm. Yield of dinitroaniline is 90%, yield of dinitrophenol is 65%. For more information on 2,4-dinitrophenol as well as an alternative synthesis please see its section here.

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