The general procedure for the synthesis of 2,4,5-trimethoxyaniline from 1,2,4-trimethoxy-5-nitrobenzene was as follows: 103.0 g (0.4831 mol) of 1,2,4-trimethoxy-5-nitrobenzene, 7.5 g (0.0014 mol) of palladium-carbon catalyst (5.0% dry palladium content) and 0.82 g (0.0059 mol) of potassium carbonate were placed in a hydrogenation reactor and 723.6 g (8.2125 moles) of 1,4-dioxane was added as solvent. The reaction temperature was controlled between 75-85 °C, the stirring speed was maintained at 1400-1500 rpm, and the hydrogen pressure was maintained at 2.0-2.2 MPa, and the reaction was terminated after 1 hour. Upon completion of the reaction, the reaction mixture was filtered to recover the palladium-carbon catalyst. The filtrate was concentrated until a solid precipitated, 154.5 mL of toluene was added, the mixture was stirred and cooled to 5 °C and filtered to obtain a purple solid. The purple solid was dried under vacuum at 25-30 °C to give a final 84.3 g of 2,4,5-trimethoxyaniline. The yield of the catalytic hydrogenation reaction was 95.2%. The purity of the product was 98.0% by HPLC analysis, and the melting point was 94.2-95.0 °C, confirming the high purity of the resulting 2,4,5-trimethoxyaniline.
