The reaction of an aromatic heterocycle with a proton is called a protonation. One of articles about this theory is 《Bromo derivatives of 1-methylglyoxaline and the constitution of “”chloroxalmethylin””》. Authors are Balaban, I. E.; Pyman, F. L..The article about the compound:5-Chloro-1-methyl-4-nitroimidazolecas:4897-25-0,SMILESS:C1=NC(=C(Cl)[N]1C)[N+]([O-])=O).Name: 5-Chloro-1-methyl-4-nitroimidazole. Through the article, more information about this compound (cas:4897-25-0) is conveyed.
cf. C. A. 16, 2863. Bromination of 18 g. 1-methylglyoxaline in 60 cc. CHCl3 with 36 g. Br in 60 cc. CHCl3 at 5-10° gave 10.4 g. 2,4,5-tribromo-1-methylglyoxaline (I), m. 93-4.5° (Wallach, Ber. 16, 537, gives 88-9°), 0.49 g. (as picrate) of 4,5-dibromo-1-methylglyoxaline (II), m. 79-80°, and 23.3 g. (as picrate) of unchanged base. I.HCl, m. 190-200°, dissociates in H2O. I is recovered to the extent of 90% after heating with 1 mol. Na2SO3 in 20% aqueous solution for 5 hrs., 1% of II also being isolated. II was further prepared by heating 4,5-dibromo-1-methylglyoxaline with Me2SO4 and from (CONHMe)2 and PBr5 (7% and 11% with 1 and 2 mols. PBr5, resp.). II.HCl, crystallizing with 2 H2O, lost in vacuo over H2SO4, and then m. 179°; HNO3 salt, m. 153°; picrate, yellow, m. 148-9°, soluble in 6 parts hot EtOH or 30 parts boiling H2O. Methylation of 4(5)-bromoglyoxaline gives 51% III and 1.5% IV (ratio 34:1), separated by fractional crystallization of the picrates from EtOH. 5-Bromo-1-methylglyoxaline (III), b15 128°, m. 45-6°, deliquescent; HCl salt, needles with 0.5 H2O, lost at 100° and then m. 155°; HNO3 salt, anhydrous prisms, m. 155° (effervescence) soluble in 4 parts boiling H2O; H oxalate salt, needles with 0.5 H2O, lost in vacuo over H2SO4 and then m. 147°; picrate, yellow needles, m. 190°. The 4(?)-sulfonic acid, m. 284°, results in 78% yield; it is soluble in 55 parts boiling H2O, almost insoluble in cold H2O. Heating 0.38 g. of the acid with 5 cc. 30% H2SO4 for 3 hrs. at 170° gave 0.11 g. III (as picrate). The 4-nitro derivative (V) of III (80% yield), m. 180°, soluble in 85 parts boiling H2O; HCl salt, m. 155° and decomposed by H2O. V crystallines unchanged from aqueous picric acid. With aqueous Na2SO3 V yields 4-nitro-1-methylglyoxaline-5-sulfonic acid, m. 254° (decomposition); Na salt, fine needles. Hydrolysis of the acid by heating with 30% H2SO4 gives 4-nitro-1-methylglyoxaline; this establishes the orientation of these bases directly and of IV indirectly. III condenses with HCHO, by heating 6 hrs. at 130°, to give 5-bromo-2-hydroxymethyl-1-methylglyoxaline, m. 143° and soluble in 15 parts boiling H2O (yield, 42%); picrate, yellow needles, m. 165-6°. Reduction with HI and red P gives 1,2-dimethylglyoxaline. Either III or IV, heated with MeI, gives 4(5)-bromo-1,3-dimethylglyoxalinium iodide, m. 202-4°, soluble in 8 parts hot EtOH; distillation at 15 mm. and 235° gave 43% IV and some III. 4-Bromo-1-methylglyoxaline (IV) is an oil; HNO3 salt, prisms, m. 155°, soluble in about 3 parts boiling H2O; picrate, yellow needles, m. 179°, soluble in 7 parts hot EtOH. The 5(?)-sulfonic acid (yield, 77%) crystallines with 1 H2O, m. 256° (decomposition), soluble in 15 parts boiling H2O. The 5-nitro derivative (VI) (yield, 54%), m. 105°, soluble in 40 parts boiling H2O. Methylation of 7 g. 4(5)-bromo-5(4)nitroglyoxaline (VII), gave 1.7 g. VI and 1.4 g. unchanged material. Na2SO3 (20% aqueous solution) reacts with VII to give 4(5)-nitroglyoxaline-5(4)-sulfonic acid, decomposes 300° (yield, 88%); Na salt, fine needles. “”Chloroxalmethylin,”” prepared according to W., gives a HNO3 salt, m. 145° which, heated with concentrated H2SO4 1.5 hrs. at 100°, gives 5-chloro-4-nitro-1-methylglyoxaline, m. 147°, soluble in 40 parts boiling H2O; it is therefore 5-chloro-1-methylglyoxaline.
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Reference:
Nitrile – Wikipedia,
Nitriles – Chemistry LibreTexts