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446 CHEMISTRY AND TECHNOLOGY OF EXPLOSIVES

900 kg of molten nitronaphthalene direct from the nitrator, together with 2600 kg

of the above nitrating mixture, is run into the nitrator. The introduction of nitro-

naphthalene and acid requires about 8 hr. During this procedure a temperature

of 57°C is maintained. Then the nitrator contents are stirred for 2 hr at 57°C.

After cooling to 40°C during a period of 4 hr the nitrator is discharged at the bottom.

During the cooling process the product solidifies to form granules, which can easily

be atered off from the acid on a vacuum filter.

It may happen that trinitronaphthalene becomes lumpy during cooling, thus

rendering discharge difficult. If this occurs, the nitrator contents should be reheated

to 57°C and then slowly cooled to 45°C prior to being discharged. If this proves

ineffective a considerable part of the acid is removed from the nitrator (the acid

being the lower layer and trinitronaphthalene the upper), and in its place spent

acid from mononitration is introduced. The mixture is then heated to 50-60°C

and even to 70°C (the temperature should be the higher the more the mononitration

acid has been used) and drawn off into a filter. The filtered nitration product is trans-

ferred to a tank containing water. During washing the lumpy material disintegrates,

forming granules.

The end product usually contains about 15.6% of nitrogen (the lowest content

admissible is 15.1%), while the theoretical content should be 15.97% of N. The

melting point of the product ranges from 108°C at the beginning to 124°C by the

end of melting.

Although the process is carried out at low temperature it is not quite safe. At

the St. Chamas factory an explosion of the nitrator contents occurred in 1940.

The accident was caused by a fault in the stirrer. Shortly before the explosion took

place an evolution of brown nitrogen oxides had been observed, as well as a local

temperature rise up to 77°C, which meant it was 20°C too high. Inflammation

of the product in the nitrator then followed.

After the accident additional agitating equipment for mixing with compressed

air was installed, as a stand-by for use in the event of a breakdown of the stirrer.

2-METHYL-1-NITRONAPHTHALENE

m. p. 81°C

Since 2-methylnaphthalene has been made available through improvements
in coal tar separation methods, considerable interest in the derivatives of this

hydrocarbon has been recently shown. Nitration is obviously one of the ways of

transforming this raw-material into products of greater commercial application.
As long ago as 1884, Schulze [38] examined the process of nitration of 2-methyl-

naphthalene with nitric and sulphuric acids and reported 1-nitro-2-methylnaph-