How many more polymorphs of ROY remain undiscovered?

With 12 crystal forms, 5-methyl-2-[(2-nitrophenyl) amino]-3-thiophenecabonitrile (a.k.a. ROY) holds the current record for the largest number of fully characterized organic crystal polymorphs. Four of these polymorphs were discovered or characterized since 2019,...

A Novel 3E Method for Synthesis of 5-nitro 2-diethylamino 6-methyl pyridine Organic Crystal by Nitration of 2-diethylamino 6-methyl pyridine with H2SO4/HNO3

4-nitro 2-diethylamino 5-methyl pyridine (P-NitroC10N2H16) as an organic crystal which is the useful intermediate for pharmaceutical synthesis and for production of organic materials, which was usually synthesized by nitration of 2-diethylamino 5-methyl pyridine with H2SO4/HNO3 mixtures, followed by extraction, chromatography column separation and recrystallization three-step procedures. Here an innovation process for synthesizing 4-nitro 2-diethylamino 5-methyl pyridine crystal from the nitration of C10N2H16 without needing chromatography column separation step is presented. The novel organic synthesis process is more ecologic, economical, and environmentally-friendly (3E) than the traditional organic synthesis process since the chromatography column separation process is a material-consuming and energy-consuming step, which needs to dispose of a large amount of wasted silica beads.