The reaction of an aromatic heterocycle with a proton is called a protonation. One of articles about this theory is 《[Haloderivatives of] pyridine[carboxylic acids]》. Authors are Dohrn, M.; Diedrich, P..The article about the compound:3,4,5-Trichloropyridinecas:33216-52-3,SMILESS:C1=NC=C(C(=C1Cl)Cl)Cl).Category: bromides-buliding-blocks. Through the article, more information about this compound (cas:33216-52-3) is conveyed.
3,5-Diiodochelidamic acid (I) [chloride, m. 149°; Me, m. 173°, Et (II), m. 169°, and benzyl, m. 200° (decomposition), esters] and Me2SO4 in aqueous KOH at 35° give 3,5-diiodo-N-methylchelidamic acid (III), m. 174° (decomposition) (Me ester, m. 194-5% while the Ag salt of II and Mel in xylene afford the Et ester, m. 100-1°, of 3,5-diiodo O-methylchelidamic (3,5-diiodo-4-methoxypyridine-2,6-dicarboxylic) acid, decomposes 176°. 3,5-Diiodo-4-ethoxy-, m. 174° (decomposition) (Me ester, m. 131°), -propoxy-, m. 156° (decomposition) (Me ester, m. 89°), -butoxy-, m. 145° (decomposition) (Me ester, m. 82°), and benzyloxy-, m. 167° (decomposition) (Me ester, m. 120°), -pyridine-2,6-dicarboxylic acids are prepared similarly. III heated at 170° gives 3,5-diiodo-N-methyl-4-pyridone, M. 214-5°, also prepared from 3,5-diiodo-4-pyridone (IV), m. 321° (decomposition), and Me2SO4 in aqueous KOH; IV is obtained from 4-pyridone and ICl in dilute HCl and by hydrolysis of its N-Ac derivative, m. 245° (decomposition) [from I and boiling AC2O]. I and IV with ClSO3H give the corresponding N-sulfo derivatives, m. 210° (decomposition) and 183° (decomposition), resp., hydrolyzed by H2O to H2SO4 and I and IV. 3,5-Diiodo-4-pyridone-N-acetic acid, m. 240° (decomposition), is prepared from IV and CH2ClCO2H. 4-Pyridone-2-carboxylic acid (V) and I in aqueous KOH give the 3,5-di-I derivative, decomposes 250° [N-Me, m. 159° (decomposition), and NCH2CO2H, m. 223° (decomposition), derivatives]; 2-pyridone-6-carboxylic acid similarly affords the 3,5-di-I derivative, decomposes 272° [N-Me derivative, m. 194° (decomposition)], also formed by iodination of 2-pyridone-5,6-dicarboxylic acid. 3,5-Dichloro-, m. above 300° (N-Me derivative, m. 166°), and 3,5-dibromo-, m. above 300° [N-Me derivative, m. 170° (decomposition)], -4-pyridone-2-carboxylic acids are obtained by halogenation of V. Et 3,5-dichlorochelidamate, m. 96°, and PCl5, give the Et ester, m. 35°, of 3,4,5-trichloropyridine-2,6-dicarboxylic acid, decomposes 150°. 4-Chloro-, m. 232° (decomposition) (Et ester, m. 111°), and 4-bromo-, m. 186° (decomposition) (Et ester, m. 98-9°), -3,5-diiodopyridine-2,6-dicarboxylic acids are prepared from II and PCl5 + POCl3 and PBr5, resp. The Et ester of 3,4,5-tri-bromopyridine-2,6-dicarboxylic acid (m. 180° (decomposition)) m. 67°. 3,4,5-Trichloropyridine, m. 76-7°, from 3,5-dichloro-4-pyridone, PCl5, and POCl3, at 125°, with EtOH-KHS gives 3,5-dichloro-4-thiolpyridine, m. 188°, oxidized by alk. KMnO4 to 3,5-dichloro-pyridine-4-sulfonic acid, m. above 300°. 4-Chloro-3,5-dibromo-, m. 98°, and 4-chloro 3,5-diiodo-, m. 175°, -pyridines are similarly converted by way of 3,5-dibromo-, m. 222°, and 3,5-diiodo-, m. 206° (decomposition), -4-thiolpyridines into 3,5-dibromo- (VI) and 3,5-diiodo- (VII), decompose 308°, -pyridine-4-sulfonic acids. 3,5-Dibromo- and 3,5-diiodopyridine-2-sulfonic acids, both decompose above 300°, are prepared similarly. VI and aqueous NH3 (d. 0.91) at 130° give 3,5-dibromo-4-aminopyridine, m. 169-70°;3,5-dibromo-4-anilino-, m. 167°, and -4-o-carboxyanilino-, m. 252° (as Et ester, m. 105-6°), -pyridines are formed with PhNH2 and o-NH2C6H4.CO2Et, resp. When an aqueous solution of VI is heated, 3,5,3′,5′-tetrabromo-N-4′-pyridyl-4-pyridone, m. above 300°, and SO2 are formed. 3,5,3′,5′-Tetraiodo-N-4′ -pyridyl-4-pyridone, decomposes above 300°, is obtained similarly from VII.
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Reference:
Bromide – Wikipedia,
bromide – Wiktionary