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Org. Synth. 1927, 7, 68
DOI: 10.15227/orgsyn.007.0068
NITROGUANIDINE
[Guanidine, nitro-]
Submitted by Tenney L. Davis
Checked by H. T. Clarke and Ross Phillips.
1. Procedure
To 500 cc. (Note 1) of concentrated sulfuric acid (sp. gr. 1.84), previously cooled in a freezing mixture, is added, in small portions and with hand stirring, 560 g. of crude (Note 2) guanidine nitrate (obtained from 210 g. of dicyanodiamide as described on p. 302). The temperature is not allowed to rise above 20° during the addition. When all has been added, the milky mixture is allowed to stand at room temperature with occasional stirring until it is homogeneous and free from crystals (Note 3). It is then poured with stirring into 6 l. of a mixture of cracked ice and water. The precipitated nitroguanidine is filtered, washed free from acid, and recrystallized from the least possible amount (4–5 l.) of boiling water (Note 4). The yield (Note 5) is 380–390 g. (73–75 per cent of the theoretical amount, based on the dicyanodiamide used). The product melts with decomposition at about 232° (Note 6).
2. Notes
1. It has been found in checking that the use of 800 cc. of acid, though not necessary, gives a much less viscous solution, which becomes homogeneous more rapidly.
2. This contains ammonium nitrate, which, however, does not interfere with the reaction.
3. The mixture has to stand fifteen to twenty hours before solution is complete.
4. The solution should be allowed to cool slowly, preferably overnight, when the nitroguanidine separates in long needles which resemble sublimed phthalic anhydride. The mother liquor contains only 3–4 g. per liter, and may be discarded.
5. In checking, yields amounting to 85–90 per cent of the theoretical quantity were obtained from pure guanidine nitrate.
6. Melting points varying between 220° and 250° have been obtained on the same sample, according to the rate of heating.
3. Discussion
Nitroguanidine can be prepared by the nitration of guanidine salts by means of nitric acid,1 or by the action of concentrated sulfuric acid, or fuming nitric acid upon guanidine nitrate.2 The nitration of guanidine thiocyanate yields a product which retains a small proportion of sulfur compounds, and the nitration of the sulfate requires vigorous treatment and gives poor yields. The procedure described, which yields the alpha form,3 is simple and economical, and furnishes a good yield. A detailed study of the preparation from guanidine nitrate and sulfuric acid has been published.4
This preparation is referenced from:

References and Notes
  1. Thiele, Ann. 270, 16 (1892).
  2. Jousselin, Compt. rend. 88, 1087 (1879); Pellizzari, Gazz. chim. ital. 21 (II), 406 (1891); Ewan and Young, J. Soc. Chem. Ind. 40, 109 T (1921); Kato, Sugino, and Koidzumi, J. Electrochem. Assoc. (Japan) 2, 187 (1934) [C. A. 28, 7250 (1934)].
  3. Davis, Ashdown, and Couch, J. Am. Chem. Soc. 47, 1063 (1925).
  4. Smith, Sabetta, and Steinbach, Ind. Eng. Chem. 23, 1124 (1931).

Appendix
Chemical Abstracts Nomenclature (Collective Index Number);
(Registry Number)

dicyanodiamide

sulfuric acid (7664-93-9)

nitric acid (7697-37-2)

phthalic anhydride (85-44-9)

ammonium nitrate

Guanidine nitrate (506-93-4)

Nitroguanidine,
Guanidine, nitro- (556-88-7)

guanidine thiocyanate