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568 CHEMISTRY AND TECHNOLOGY OF EXPLOSIVES

of tetranitrocarbazole with a certain quantity of 3,3’,5,5’-tetranitro-2,2’-dimetho-

xydiphenyl (V). The sequence of the reactions was as follows:

III IV

V I (3)

MANUFACTURE OF 1,3,6,8-TETRANITROCARBAZOLE

In a method applied at Höchst, 1896 kg of 96% sulphuric acid are charged into

the sulphonator, followed by 950 kg of commercial grade carbazole (88-95°

purity). The whole is stirred at room temperature for 50 min. Then the temperature

is raised to 95°C and stirring is continued until a sample taken from the sulphonator

dissolves completely in water. At this stage of the process disulphonic acid is formed.

Then the sulphonator contents are cooled to 70°C and the remainder of the sulphuric

acid, i.e. 1561 kg (the total quantity being 3430 kg) is added. Further sulphonation

takes place, resulting in the formation of 1,3,6-trisulphonic acid.
It has been proved that carrying out the reaction in two stages, as described
above, makes the sulphonation process proceed more quietly and prevents the
SO 3 H group from entering position 7 (otherwise, the sulpho group in position
7 would not be substituted by a nitro group, causing the nitration product to remain
soluble in water).
A two stage process is applied for the nitration of the sulphonic acid obtained.
The product is transferred to nitrator I and here half the total nitrating acid is added.
Then half the contents of nitrator I are transferred to nitrator II followed by the
second half of the nitrating acid. The sulphonated product is transferred from the
sulphonator to nitrator I, containing half of the previous batch, for repeating
the first nitration stage, then half of this reaction mixture is transferred to ni-
trator II, and so on.
Nitrator I contains half of the previous batch to which the sulphonator con-
tents and a portion of nitrating acid, consisting of 870 kg of concentrated nitric
acid and 4350 kg of 20% oleum, have been added. The nitrating acid should be
run into the nitrator at a temperature of 40°C (vigorous cooling is necessary).
This nitration stage, including the transfer of the sulphonated product, takes about

8 hr.
The other half of the contents of nitrator I is conveyed to nitrator II and the
second half of the nitrating mixture, consisting of 870 kg of concentrated nitric
acid and 4350 kg of 20% oleum, is run in, a temperature of 50°C being maintained.