Process for the preparation of dinitrotoluene

A single stage, continuous process for the production of isomeric mixtures of dinitrotoluene comprising

• a) reacting
• (1) toluene with
• (2) a nitrating acid composed of
• (i) from about 80 to about 100% by weight of an inorganic component made up of
• A) from about 60 to about 90% by weight of sulfuric acid,
• B) from about 1 to about 20% by weight of nitric acid, and
• C) at least 5% by weight of water, and
• (ii) from about 0 to about 20% by weight of an organic component containing
• A) from about 70 to about 100% by weight of dinitrotoluene isomers, and
• B) from about 0 to about 30% by weight of by-products
• under adiabatic conditions and in amounts such that the molar ratio of nitric acid to toluene is maintained at a level of at least 2:1,
• b) continuously removing reaction mixture from the reactor at a temperature of at least 120.degree. C.,
• c) separating the reaction mixture removed in b)into an upper product phase and a lower acid phase,
• d) working up the product phase separated in c) to recover dinitrotoluene,
• e) removing at least 10% of water present in the acid phase separated in c) by flash evaporation,
• f) adding from about 50 to about 100% by weight of nitric acid to the acid phase from e) and
• g) returning the acid phase of f) to a).