The general procedure for the synthesis of 2,4,6-trimethyl-1,3-benzenediamine from 1,3-dinitro-2,4,6-trimethylbenzene is as follows: In a 1000 L coil-cooled nitrification kettle, 114 kg of homotrimethylbenzene was added and mixed with 700 kg of mixed acid (H2SO4 and HNO3 in the ratio of 75:25 by weight) under stirring. The reaction temperature was controlled to be 20°C with continuous titration for 35 minutes, followed by raising the temperature to 90°C and maintaining it for 35 minutes. The reaction was layered upon completion and the spent acid was used for the next batch of nitrification. To the organic layer, 500 kg of water and 2 kg of caustic soda were added, stirred for 1 hour and layered. A further 500kg of water was used to wash 2,4,6-trimethyl-m-dinitrobenzene. The washed 2,4,6-trimethyl-m-dinitrobenzene was added to a 1000L autoclave with 10kg Ni catalyst and 320kg methanol. After replacing the gas in the kettle with nitrogen and hydrogen, the temperature was raised to 65°C to start stirring and the hydrogenation reaction was carried out. The hydrogenation pressure was controlled to be 4MPa, the temperature was 80°C, and the hydrogenation reaction lasted for 1 hour. At the end of the reaction, hydrogen was discharged, methanol was evaporated, crystallized by cooling and filtered to obtain 2,4,6-trimethyl-m-phenylenediamine. The product was dried to obtain 135 kg with 99.7% purity and 94.7% yield.
