Nitration of nitronaphthalene to trinitronaphthalene

At the St. Chamas plant, the nitrator is of 4 m3 capacity, equipped with a propeller stirrer (100 r. p. m.) and with a jacket for cooling or heating. There is an outlet 80 mm in diameter at the bottom of the nitrator for discharging the contents. 

The nitrator is charged with 800 kg of the spent acid from trinitration and 1330 kg of a mixture  

This mixture has an exceptionally high content of nitric acid, which is of great importance to obtain the required high degree of nitration. 

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. 

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