The Chemistry of Powder and Explosives - Sciencemadness Dot Org

384 NITROAMINES AND RELATED SUBSTANCES
becomes colorless again when the reduction is complete. After all the
zinc has disappeared, 1 mol of concentrated nitric acid is added, then
1 mol of benzaldehyde, and the mixture is shaken and scratched to
facilitate the separation of the heavy granular precipitate of benzalaminoguanidine
nitrate. The product, recrystallized from water or from
alcohol, melts when pure at 160.5°.
Nitroguanidine and nitrosoguanidine both give a blue color
with the diphenylamine reagent, and both give the tests described
below, but the difference in the physical properties of the substances
is such that there is no likelihood of confusing them.
Tests for Nitroguanidine. To 0.01 gram of nitroguanidine in 4 cc. of
cold water 2 drops of saturated ferrous ammonium sulfate solution is
added, then 1 cc. of 6 N sodium hydroxide solution. The mixture is
allowed to stand for 2 minutes, and is filtered. The filtrate shows a
fuchsine color but fades to colorless on standing for half an hour. Larger
quantities of nitroguanidine give a stronger and more lasting color.
One-tenth gram of nitroguanidine is treated in a test tube with 5 cc.
of water and 1 cc. of 50% acetic acid, and the mixture is warmed at
40-50° until everything is dissolved. One gram of zinc dust is added,
and the mixture is set aside in a beaker of cold water for 15 minutes.
After filtering, 1 cc. of 6% copper sulfate solution is added. The solution
becomes intensely blue, and, on boiling, gives off gas, becomes
turbid, and presently deposits a precipitate of metallic copper. If, instead
of the copper sulfate solution, 1 cc. of a saturated solution of
silver acetate 12 is added, and the solution is boiled, then a precipitate
of metallic silver is formed.
Many of the reactions of nitroguanidine, particularly its decomposition
by heat and the reactions which occur in aqueous
and in sulfuric acid solutions, follow directly from its dearrangement.
13 Nitroguanidine dearranges in two modes, as follows.
:NH2-NO2 + HNCNH =^ NH2CN
Cyanamlde
/NO, /NO2
C(NH)-N