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538 CHEMISTRY AND TECHNOLOGY OF EXPLOSIVES

Dinitrosoresorcinol is oxidized with 50% nitric acid at a temperature be-

low 0°C. Moist, freshly prepared dinitrosoresorcinol is charged into the reactor,

containing nitric acid cooled down to -5°C. When calculating the concentration

of nitric acid, the water content in dinitrosoresorcinol should be taken into account.

Simultaneously with the dinitrosoresorcinol concentrated nitric acid is introduced

into the reactor to keep the concentration of the acid in the reactor constant. After

the reaction has been completed, the reactor contents are run out into icy water.

The volume of the water containing ice should be several times as large as that

of the product. Dinitroresorcinol is precipitated and is separated on a vacuum filter

and washed with a small quantity of cold (ca. 0°C) water. The crude product contains

some trinitroresorcinol. By crystallization from hot water a product is obtained

which should not melt below 147°C. The yield of the reaction, calculated on the

resorcinol used, is about 30% of the theoretical.

For the preparation of the divalent lead salt a moist product is used; its water

content should be determined exactly.

TRINITRORESORCINOL (STYPHNIC ACID)

Physical properties

Trinitroresorcinol (m. p. 175.5°C), also known as styphnic acid, is a yellow

crystalline product which dyes animal fibres intensely. 100 ml of water dissolves

0.641 g of it at 14°C, and 1.136 g at 62°C.

More recent solubility data by Aubertein and Emeury [29] are: in 100 g of water

0.45 g of styphnic acid are soluble at 15°C 0.55-0.58 g at 20°C 0.68-0.69 g at 25°C.

Knox and Richards [30] determined the solubility of styphnic acid in nitric

acid of various concentrations at 25°C, expressed as the “normality” of the HNO 3

solutions. Aubertein and Emeury have recalculated their results expressing the

solubility in a more convenient way:

HNO 3 , wt. % 0 10.67 41.91 55.9 69.57

Solubility in 100 g of the acid, g 0.53 0.034 0.125 0.32 1.37

Aubertein and Emeury have also determined the solubility of styphnic acid
in sulphuric acid of different concentrations at 25°C:

H 2 SO 4 , wt. % 0 6 20 50 80 92

Solubility in 100 g of the acid, g 0.65 0.07 0.01 0.10 0.13 0.13

The solubility of styphnic acid in nitric acid-sulphuric acid mixtures is very low.