In organic chemistry, atoms other than carbon and hydrogen are generally referred to as heteroatoms. The most common heteroatoms are nitrogen, oxygen and sulfur. Now I present to you an article called Pyridotriazoles and pyridoimidazoles. II. 4,5-Diamino-3-picoline and 3,4-diamino-2,6-lutidine derivatives, published in 1967, which mentions a compound: 18232-91-2, mainly applied to pyridotriazoles; pyridoimidazoles; triazoles pyrido; imidazoles pyrido, Quality Control of 2-Chloro-5-methylpyridine-3,4-diamine.
A mixture of 3-methyl-4-aminopyridine in 120 ml. concentrated H2SO4 (d. 1.84) was treated portionwise, at 0°, with 48 ml. HNO3 (d. 1.52) and the mixture kept 1 hr. at room temperature, poured into 300 g. crushed ice, and neutralized with concentrated ammonia to pH 7 to give 32 g. 3-methyl-4-nitraminopyridine (I), m. 212° (H2O). When heated 5 hrs. at 50° and worked up as above, 30 g. I afforded 17.5 g. 3-methyl-4-amino-5-nitropyridine (II), m. 193° (H2O). Reduction of 3 g. II in 100 ml. AcOH with 6 g. powd. Fe, 45 min. at reflux temperature, followed by treatment with a few drops of aqueous HgCl2 and 3 g. Zn dust, neutralization with concentrated KOH, and extraction with Et2O gave 2 g. 3-methyl-4,5-diaminopyridine (III), m. 149° (C6H6-alc.); picrate m. 198°. A solution of 3 g. III in 25 ml. H2O and 1 ml. concentrated H2SO4 was diazotized at 0° with 2.8 g. NaNO2 in 20 ml. H2O and the mixture kept 1 hr. at room temperature, concentrated to the half its original volume, and neutralized with KHCO3 to give 2.4 g. 3-methyl-4,5-pyridotriazole (IV, X = H), m. 260° (H2O). When refluxed 6 hrs., concentrated in vacuo, diluted with 10 ml. H2O, neutralized with KHCO3 to pH 7, then evaporated to dryness, and extracted with absolute alc., a solution of 2 g. III and 4 ml. 100% freshly distilled HCO2H afforded 0.8 g. 3-methyl-4,5-pyridoimidazole (V, X = H), m. 255°. Similarly prepared were the following (compound, m.p., and % yield given): 2,4-dimethyl-4-nitraminopyridine, 206° (decomposition), 93.5; 2,6-dimethyl-3-nitro-4-aminopyridine, 126°, 47.5-78.8; 2,6-dimethyl-3,4-pyridotriazole (VI), 267°, 70; 2,6-dimethyl-3,4-pyridoimidazole (VII), 208°, 56; 3-methyl-6-chloro-4,5-pyridotriazole (IV, X = Cl) (VIII), above 320°, 72. Reduction of 3 g. II with 48 g. SnCl2 in 15 ml. concentrated HCl gave 4 g. 3-methyl-4,5-diamino-6-chloropyridine (IX), m. 157° (H2O). A solution of 1.5 g. IX and 3 ml. hydrazine hydrate in 25 ml. absolute alc. refluxed 3 hrs. afforded 1 g. 3-methyl-6-hydrazino-4,5-pyridotriazole (IV, X = NHNH2), m. 265° (H2O). IX (2 g.) in 4 ml. 100% HCO2H refluxed 6 hrs. and worked up as above gave 1.4 g. 3-methyl-6-hydroxy-4,5-pyridoimidazole (V, X = OH) (X), m. >320°. Heating 2 g. X in 10 ml. POCl3 3 hrs. on a steam bath afforded 1.4 g. 3-methyl-6-chloro-4,5-pyridoimidazole (V, X = Cl) (XI), m. 256° (H2O). When refluxed with hydrazine hydrate 2 g. XI yielded 63% 3-methyl-6-hydrazino-4,5-pyridoimidazole (V, X = NHNH2), m. 220°. Reduction of 2 g. 2,6-dimethyl-3-nitro-4-aminopyridine in 50 ml. hot AcOH with 4 g. Sn led to 1.1 g. 2,6-dimethyl-3,4-diaminopyridine, m. 181° (C6H6); picrate m. 215°.
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Reference:
Thiazole | C3H3NS – PubChem,
Thiazole | chemical compound | Britannica