Toluene diamine from non-washed dinitrotoluene

摘要

This invention relates to an improvement in a process for preparing toluene diamine. The improvement resides in a process which is capable of permitting reduction of dinitrotoluene to toluene diamine without prior alkaline treatment for removal of nitrocresols in the dinitrotoluene. In carrying out the improvement the feed dinitrotoluene is water washed to remove HNO3 to a level below 6000 ppm, and the catalytic conversion of dinitrotoluene to toluene diamine is done continuously. Dinitrotoluene is charged to a reaction vessel containing a liquid carrier and reduced with hydrogen at constant pressure, the dinitrotoluene being added at a rate to maintain a concentration of dinitrotoluene of 0.0001 to 25% by weight of the total reactor contents while the hydrogenation catalyst is maintained at a level from about 0.1 to 3% based on the weight of reactor contents.