To a 1000 mL dry three-necked flask were sequentially added 60 g (0.416 mol) of methyl isobutyrylacetate, 120 g (1.288 mol) of aniline and 6 g of 4-dimethylaminopyridine (DMAP). Stirring was turned on and the temperature was slowly increased to an internal temperature of 100 °C and the reaction was maintained at this temperature for 16 hours. During the reaction, the methanol generated was collected by a fractionation device. At the end of the reaction, the system was cooled down to 70 °C and the unreacted aniline was recovered by distillation under reduced pressure, and a total of 74.7 g of aniline was recovered with 92% recovery. After the remaining reaction solution was concentrated to about 100 g, 1 kg of water was added, cooled to 30 °C and stirred to crystallize for more than 5 hours. The product was filtered, the cake was washed with water for 3 times, and dried to give a white solid product of 82.3 g. The product was analyzed by HPLC with a purity of 99.8% and a yield of 96.4%.
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