Process for the production of dinitrotoluene

A two-stage process for the continuous production of isomer mixtures of dinitrotoluene comprising

• A) reacting
• 1) toluene with
• 2) nitrating acid composed of
• a) from 80 to 100% by weight of inorganic materials which include:
• (i) from about 60 to about 90% by weight of sulfuric acid,
• (ii) from about 1 to about 20% by weight of nitric acid, and
• (iii) at least 5% by weight of water and
• b) from 0 to about 20% by weight of organic materials which include:
• (i) from about 70% by weight of isomers of nitrotoluene and
• (ii) from 0 to about 30% by weight of by-products of the nitration reaction
• isothermally in a continuously operated reactor at a temperature of from about 0 to about 100.degree. C. in amounts such that the molar ratio of nitric acid to toluene is at least 0.7:1 but no greater than 1.2:1,
• B) separating the reaction mixture from A) into an organic phase and an acid phase,
• C) reacting the organic phase separated in B) under adiabatic conditions at a temperature of from about 20 to about 200.degree. C. with a nitrating acid which is made up of:
• a) from about 80 to about 100% by weight inorganic materials which include:
• (i) from about 60 to about 90% by weight sulfuric acid,
• (ii) from about 1 to about 20% by weight nitric acid, and
• (iii) at least 5% by weight water, and
• b) from 0 to about 20% by weight organic materials which include:
• (i) from about 70 to about 100% by weight isomers of nitrotoluene and
• (ii) from 0 to about 30% by weight by-products of the nitration reaction,
• in amounts such that the molar ratio of nitric acid to mononitrotoluene is at least 0.7:1 but no greater than 1.2:1,
• D) separating the reaction mixture from C) into an organic phase and an acid phase,
• E) removing at least 5% by weight of water from the acid phase separated in D),
• F) adding 50-100% nitric acid to the acid phase from E) and
• G) recycling the acid phase from F).