An Efficient Pathway to Synthesize Diketopyrrolopyrrole Pigments in Ionic Liquids

The investigation results of an efficient pathway for the synthesis of high-performance 1, 4-diketo-3, 6- diphenyl pyrrolo [3, 4-c] pyrroles pigments using diethyl succinate in ionic liquids ([BMIM][BF4], and [HMIM][BF4]) has been reported. Synthesis of 3, 6-Bis (4-chlorophenyl)-2, 5-dihydropyrrolo [3, 4-c] pyrrole-1, 4-dione using [BMIM][BF4] is more efficient (81% at 30°C) than conventional methods (70% at 105-110°C). 3, 6-Bis (4-bromophenyl)-2, 5- dihydropyrrolo [3, 4-c] pyrrole-1, 4-dione was produced in this approach with 73% yield at 30°C in 8 h reaction time instead of the previously reported (65% yield in 24 h). The production yield of 1, 4-diketo-3, 6-diphenyl pyrrolo [3, 4-c] pyrroles was not highly affected by ionic liquids, and produced in maximum 43% yield. The crystalline phase, particle sizes and morphologies of the synthesized pigments have also been reported.