Nitric Acid → 4-Nitrotoluene

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Reaction Steps

Dinitrotoluene is an important intermediate in producing toluenediisocyanate based polyurethanes. One of the conventional processes for producing dinitrotoluene is referred to as the mixed acid nitration process wherein toluene is reacted with nitric acid in the presence of sulfuric acid in a mononitration zone to produce the intermediate product, mononitrotoluene (MNT), which then is separated from the spent acid and the recovered mononitrotoluene contacted with nitric acid in the presence of sulfuric acid to form dinitrotoluene in a dinitration zone. Dinitrotoluene (DNT) then is separated from the aqueous phase and the spent sulfuric acid purified and concentrated. Typical, product specifications (weight %) for commercial grade dinitrotoluene generally will be greater than 98.5% dinitrotoluene, less than 0.1% mononitrotoluene, less than 0.1% trinitrotoluene, less than 0.1% by-products, less than 1.0% water and yield of toluene to dinitrotoluene greater than 98% at conversion levels of >99.9%. The isomer content of product DNT contains a minimum of 95% (on a water free basis) 2,4-plus 2,6-isomer with the balance of the DNT being made up of 2,3-; 3,4-; 2,5-; and 3,5-isomers. The normalized 2,4-plus 2,6-isomer content is between 79.0-81.0% 2,4-isomer and between 19.0-21.0% 2,6-isomer.

Provenance & Evidence