Patent ID: 8410322

Claim:
A method for preparing dinitrotoluene from mononitrotoluene with improved decantation time comprising nitrating mononitrotoluene using a nitrating admixture which comprises nitric acid, sulphuric acid and water and which results in a bi-phase medium such that the weight ratio between the aqueous phase and the organic phase is at least 1.2, separating the organic and aqueous phases of the bi-phase medium, wherein the nitration of the mononitrotoluene is carried out using a nitrating admixture which comprises 20 to 44.5% of nitric acid, 55 to 70% by weight of sulphuric acid, a maximum of 10% by weight of water resulting in a bi-phase medium, separating the organic and aqueous phases of the bi-phase medium; and wherein the separated aqueous phase is recycled to a point at the end of the nitration reaction of the mononitrotoluene and before the separation of the organic and aqueous phases.