410 CHEMISTRY AND TECHNOLOGY OF EXPLOSIVES
are added. Thus, the quantity of HNO 3 amounts to 105% of theoretical. The
nitrating mixture is prepared from the spent acid from trinitration.
During the introduction of the nitrating mixture into the nitrator a temperature
of 30-40°C is maintained. After all the acid has been introduced and the mixture
in the reactor has been kept at 40-45°C for two hours, it is cooled to 15-20°C,
the stirrer is stopped, and after 15-20 min the nitro compound formed is separated
from the spent acid.
100 parts of m- xylene yield 130-140 parts of MNX, which corresponds to 91-
98% of theory.
For the conversion of MNX to TNX a nitrating mixture of the composition:
HNO 3 17.5%
H 2 SO 4 79.0%
H 2 O 3.5%
is added at a temperature of 10-12°C, the proportion of the reagents being 6 parts
of the nitrating mixture for 1 part of mononitroxylene. Such a proportion corre-
sponds to an excess of HNO 3 of nearly 25%.
During the first hour of the nitration process the temperature rises gradually
to 50-60°C and finally reaches 65°C. Then the temperature is raised gradually
to 110-120°C, and maintained then for 1 or l½ hr. After cooling, the trinitroxylene
is filtered off, washed with cold, and then with hot (80-90°C) water, and finally
the wet, hot product is separated from oily substance by centrifugation.
Spent acid from trinitration has the composition:
HNO 3 2-6%
H 2 SO 4 82-85%
H 2 O 11-15%
From 100 parts of MNX 170-180 parts of TNX are obtained; thus the yield is
70-80% of the theoretical.
The melting point of TNX prepared in this way is 164-166°C.Three-stage preparation of TNX†Mononitration. For 100 parts of m- xylene, separated from its isomers by sulpho-
nation, 220 parts of a nitrating mixture of the composition:
HNO 3 28%
H 2 SO 4 56%
H 2 O 16%
are used.
The nitrating mixture is prepared from spent acids from di- and tri-nitration,
by fortifying them with fresh concentrated acids.
The nitration temperature should not exceed 35°C. From 100 parts of m- xylene,
130-135 parts of MNX are obtained, i.e. the yield is 90-94% of the theoretical.
Further procedure (separation of the nitro compound from the spent acid) is similar
to that used in other nitration processes.† Soviet and French methods (according to Kravchinslcii [3] and Pascal [20] respectively).