Synthesis
General procedure for the synthesis of 4-amino phthalimide from 4-nitrophthalimide: 4-nitrophthalimide (LOOGR) was placed in a hydrogenation reactor and dissolved in 600 mL of dimethylformamide (DMF). Nickel Nguyenay catalyst (20 g, wet weight) was added to this solution and the hydrogenation reaction was initiated at 20-30 °C and 20-40 psi hydrogen pressure. After the exothermic phenomenon of the reaction was over, the hydrogen pressure was increased to 40-60 psi and the reaction temperature was raised to 40-50 °C. Upon completion of the hydrogenation reaction, the reaction mixture was filtered while hot to remove the catalyst. Subsequently, dimethylformamide was recovered from the filtrate by distillation under reduced pressure at 60-80 °C. To the residue, 500 mL of water was added and stirred for 20-30 minutes. The product was separated by filtration and dried at 60-70 °C to give 4-amino phthalimide as a yellow crystalline solid (82 g, 97% yield). Melting point: 293-295°C.
References
[1] Patent: WO2004/43919, 2004, A1. Location in patent: Page 8
[2] Patent: US2011/77394, 2011, A1. Location in patent: Page/Page column 15
[3] Patent: WO2004/43919, 2004, A1. Location in patent: Page 9
[4] ChemCatChem, 2017, vol. 9, # 6, p. 1128 - 1134
[5] Patent: CN104447496, 2017, B. Location in patent: Paragraph 0067; 0070; 0071