den Hertog, H. J. published an article in 1945, the title of the article was Derivatives of pyridine and quinoline. LIX. Bromopyridines.Product Details of 861024-77-3 And the article contains the following content:
Pyridine (I) is brominated at 300° in the vapor phase and 3-bromopyridine (II) separated by distillation 3,5-Dibromopyridine (III) seps. upon cooling the residue; it is filtered off and the filtrate (400 g.) is fractionated under 20 mm. through a 20-cm. Widmer column. Fraction (1), 95° (55 g.), was II; (2), 95-100° (25 g.), was 3,4-dibromopyridine (IV) and III; (3), 100-5° (50 g.), was III, IV, and 2,5-dibromopyridine (V); (4), 105-10° (45 g.), was III, 2,3-dibromopyridine (VI), and V; (5), 110-15° (50 g.), was VI; (6), 115-20° (50 g.), was 2,6-dibromopyridine (VII); (7), 120-25° (30 g.), was VII; (8), 125-30° (20 g.), was VII and 3,4,5-tribromopyridine (VIII); (9), 130-35° (15 g.), was VII, VIII, and 2,3,5-tribromopyridine (IX); (10), 135-140° (20 g.), was VIII and IX; (11), 140-45° (25 g.), was VIII and IX; residue (15 g.). Fraction (3) (typical treatment) was shaken with 80 ml. of 8% HCl, the insoluble portion (A) separated from the soluble portion (B) which was poured into concentrated NH4OH. The crystals which separated (10 g.), recrystallized from petr. ether, yielded 5.5 g. of IV, m. 70-1°. (A) was extracted twice with dilute HCl. The soluble part, isolated and recrystallized from EtOH (3.5 g.), was identified as III, m. 110-11°. The insoluble residue, extracted with 25% HCl (110 ml.), gave 5 g. of an insoluble residue, recrystallized from EtOH and identified as V, m. 93-4°. Fraction (5) was shaken with 100 ml. 12% HCl, and the soluble part (C) removed from the insoluble part (D). (C) contained III. (D), recrystallized from EtOH, was identified as V. The mother liquor yielded an oil which, recrystallized from benzene, then from acetone-water, yielded VI, m. 58-9°. Fraction (10), recrystallized from EtOH, yielded 3 g. VIII, m. 106.5-7.5°. The mother liquor yielded an oil which was extracted with HCl. The residue, recrystallized from EtOH, gave needles of IX, m. 44-5°. IV was obtained from fraction (2) by again distilling under 20 mm., collecting the 99-106° fraction (55 g.), extracting with 85 ml. 8% HCl, and pouring the solution into NH4OH; the resulting 13 g. oil, recrystallized from benzene, yielded 8 g. (0.4%) of IV, m. 71-2°, decomposes on distillation IV (1 g.) was heated 8 hrs. at 160° with 10 ml. NH4OH (sp. gr. 0.9) in sealed tubes, made basic, and extracted with ether. Removal of the ether left an oil which recrystallized from benzene and ligroin with difficulty. The product, 4-amino-3-bromopyridine (X), forms a picrate, m. 235-6°, which yields X, m. 69.5-70.5°, when treated with base, distilled with steam, extracted with ether, dried, and poured into petr. ether. X (0.17 g.) in 1 ml. 20% H2SO4 was reacted with 0.20 ml. Br in 1.5 ml. HOAc, made basic, extracted with ether, the ether removed, and the residue recrystallized from aqueous EtOH, yielding 4-amino-3,5-dibromopyridine (XI). IV upon standing 8 months decomposes to form a N-pyridylpyridinium compound (XII), m. 205-9°. XII heated with NH4OH (sp. gr. 0.9) 8 hrs. in a sealed tube (200°) yielded X. IV (1 g.) heated 15 min. at 140° yielded yellow crystals which, when extracted by refluxing with EtOH, yielded 1-(3-bromo-4-pyridyl)-3-bromo-4-pyridone, m. 243-4°. 2,3,6-Tribromopyridine (1.8 g.) was reduced (2 hrs., H, Pd on Norit, 5%) in 50 ml. MeOH and 2 ml. 12% NaOH, the solution made basic and extracted with ether, the ether removed, the residue treated with 10% HCl, the solution made basic with NH4OH, and the precipitate recrystallized from aqueous EtOH, yielding VI, m. 57-8°. VI (0.35 g.) was heated at 170° in a sealed tube with 8 ml. NH4OH (sp. gr. 0.9), then made basic with NaOH and extracted with ether, the ether removed, and the residue recrystallized from ligroin, yielding 2-amino-3-bromopyridine (XIV), m. 64.5-5.5°, 0.27 g. of which, dissolved in 20% H2SO4 and mixed with 0.4 g. Br in 4.5 ml. HOAc and heated 20 min., then treated with Na2CO3 solution, yielded 0.4 g. 2-amino-3,5-dibromopyridine, m. 103-4° (from ligroin). Heating 2,4-dibromopyridine with NH4OH yielded 2-amino-4-bromopyridine (XV), m. 143-4.5° (picrate, m. 262-3°) and 4-amino-2-bromopyridine (XVI), m. 97.5-8.5° (picrate, m. 129-30°). Bromination of XVI yielded 4-amino-2,3,5-tribromopyridine, m. 147-8°, and 4-amino-2,3-dibromopyridine, m. 171-3°. 2,4-Dihydroxypyridine in 48% HBr and Br yielded 3-bromo-2,4-dihydroxypyridine (XVII), m. 263.5-4.5° (decomposition). XVII with POBr3 in a sealed tube yielded 2,3,4-tribromopyridine (XVIII), m. 84-5°. The structure was proved by synthesis of XVIII from 3-bromo-2,4-dihydroxy-5-pyridinecarboxylic acid (XIX). XIX heated with 38% HCl was converted to 3-chloro-2,4-dihydroxypyridine (decomposes 310°) which, heated with POBr3, yielded 3-chloro-2,4-dibromopyridine (XX), m. 70-70.5°. XX heated with NH4OH yielded 2-aminobromochloropyridines of unknown structure. XVIII heated with NH4OH yielded 2-amino-3,4-dibromopyridine (XXI), recrystallized from aqueous EtOH, m. 128-9°, and 4-amino-2,3-dibromopyridine (XXII), recrystallized from ligroin-EtOH, m. 173-5°. XXII reduced in basic solution (H, Pd) yielded 4-amino-pyridine, m. 158°. XVIII was also prepared from 2,4-dimethoxypyridine by heating with PBr5 and POBr3. Bromination of 2,4-dihydroxypyridine yielded 3,5-dibromo-2,4-dihydroxypyridine, which, treated with 48% HBr, yielded 2,4,5-tribromopyridine (XXIII), recrystallized from aqueous EtOH, m. 66.5-7.5°. XXIII heated with NH4OH yielded 4-amino-2,5-dibromopyridine, recrystallized from aqueous EtOH, m. 147-8°. VIII when brominated at 500° yielded 2,3,4,5-tetrabromopyridine (XXIV), recrystallized from aqueous EtOH, m. 74.5-5.5°. XXIV was also prepared by heating 2,4-dihydroxypyridine with PBr5 and POBr3 for 5.5 hrs. at 120-5°. XXIV heated with NH4OH as before yielded 4-amino-2,3,5-tribromopyridine, m. 148-8.5°. A table of constants of known bromopyridines is given. The experimental process involved the reaction of 2,4-Dibromo-3-chloropyridine(cas: 861024-77-3).Product Details of 861024-77-3
2,4-Dibromo-3-chloropyridine(cas:861024-77-3) belongs to pyridine-derivatives. Several pyridine derivatives play important roles in biological systems. While its biosynthesis is not fully understood, nicotinic acid (vitamin B3) occurs in some bacteria, fungi, and mammals.Product Details of 861024-77-3