572 CHEMISTRY AND TECHNOLOGY OF EXPLOSIVES
Picramic acid or 4,6-dinitro-2-aminophenol (m. p. 169-179°C) forms dark
red crystals, readily soluble in benzene and acetic acid, but difficult to dissolve
in other organic solvents.
The compound is prepared by reacting sodium sulphide with picric acid (Girard
[44]). It is of some importance as an intermediate in the manufacture of azo dyes.It has not found any use as an explosive. being none the less a source for the initiating
explosive dinitrodiazophenol (Vol. III).
NITRO DERIVATIVES OF PHENOTHIAZINE
Phenothiazine nitrated to its tetranitro derivative was used by the Germans
during World War II as a component of a non-fusible explosive composition known
under the name of “Pressling”. Monard, Ficheroulle and Fournier [45] found the
compound to be phenothiazine tetranitrosulphoxide (I) (m. p. 368°C):
The compound may be prepared in 70% yield by the nitration of phenothiazine
with a mixture of 98% nitric acid and anhydrous sulphuric acid at 60°C. In
addition to nitration, oxidation of the sulphur atom also takes place, resulting
in the formation of the sulphoxide.
Bernthsen [46], Kehrmann and co-workers [47] and Gilman and Shirley [48]
also observed similar oxidation of the sulphur atom when nitrating phenothiazinederivatives. The oxidation of sulphur to the sulphonyl group, has been
observed in the nitration of diphenyl sulphide (p. 554). As T. Urbanski, Szyc-
Lewatiska and Kalinowski [49] found, methylene blue, when nitrated, yields deriv-
atives having a sulphonyl group (see Vol. III for more details).
LITERATURE!- A. W. HOFMANN, Jahresber. 1860, 350; Ber. 39, 1715 (1879).
- G. KÖRNER, Gazz. chim. ital. 4, 318, 354 (1874).
- F. K. BEILSTEIN and A. KURBATOV, Ann. 196, 223 (1879).
- A. F. HOLLEMAN, Chem. Revs. 1, 187 (1924-25).
- J. FR. WALKER and T. ZINCKE, Ber. 5, 114 (1872).
- J. S. MUSPRATT and A. W. HOFMANN, Ann. 57, 201 (1846).
- E. BRUNS, Ber. 28, 1954 (1895).
- RUDNEV, Zh. Russ. Khim. Obshch. 3, 121 (1871).
- ENGFLHARDT and LACHINOV, Z. Chemie 1870, 233.