Old French process

This process, as described by Pascal [5], was used in France both during World War I Mid in the early period of time between the two wars. Separate operations in the three-stage nitration process Me carried out in the following way  

Nitration of toluene to MNT ( mononitration ). To introduce one nitro group into toluene a mixture of acids is used (sp. gr. 1.672) of composition  

Toluene (650 kg) is run into a nitrator, and 1580 kg of the nitrating mixture is added with vigorous stirring. The temperature in the nitrator should be maintained at 40°C by using a cooling jacket and a coil situated inside the nitrator. After the reagents have been mixed thoroughly the temperature of the mixture should be raised to 60°C and maintained then for 45 min to 1 hr. When the reaction has been completed the nitrator contents are cooled to room temperature and the stirrer is stopped. The liquid is allowed to stand still until quiet, and then the lower layer, i.e. the spent acid, is drained off 

From 650 kg of toluene 910-950 kg of MNT is obtained, i.e. 140-146 kg for 100 kg of toluene. Since the theoretical yield is 149 kg of MNT for 100 kg of toluene, the actual yield Mnounts of 94-98% of theory. Losses are due mainly to dissolution of the nitration product in the spent acid (up to 4.5% of the total Mnount of nitro-toluene). 

Nitration of MNT to DNT ( dinitration ). The acid from the first stage of nitration, composed of  

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