Hydrogen Bromide → 2-(5-Bromo-2-thienyl)pyridine

HRID 395898Notes

Reaction equation

HRID 395898 reaction equation
[S:1]1[CH:5]=[CH:4][CH:3]=[C:2]1[C:6]1[CH:11]=[CH:10][CH:9]=[CH:8][N:7]=1.[Br:12]N1C(=O)CCC1=O.Br>COC(C)(C)C.C(O)(=O)C>[Br:12][C:5]1[S:1][C:2]([C:6]2[CH:11]=[CH:10][CH:9]=[CH:8][N:7]=2)=[CH:3][CH:4]=1

Participants

6

Reactant 3

HCID 260Hydrogen BromideHCID 67184N-bromobutanimideHCID 768322-(2'-Thienyl)pyridine

Product 1

HCID 7364832-(5-Bromo-2-thienyl)pyridineYield 82%

Reagents, catalysts & solvents 2

HCID 176Acetic AcidSolventHCID 15413tert-Butyl methyl etherSolvent

Conditions

Temperature
35 °C

Procedure

A solution of 2-thienylpyridine (1.924 kg) and N-bromosuccinimide (2.759 kg) in tert-butyl methyl ether (20.0 kg) was agitated for 15 minutes, treated with 30% HBr in acetic acid (125 g), heated to 35° C. for about 6 hours, and filtered. The wetcake was washed with tert-butyl methyl ether (12.6 kg) while maintaining the temperature of the filtrate at 30° C. to 35° C. The filtrate was washed with 5% Na2SO3 (21 kg) and 10% Na2CO3 (22 kg), concentrated to about 20 L, and diluted with isopropanol (11 kg), which caused the product to crystallize. This procedure was repeated twice more, when NMR analysis of the mother liquor indicated absence of tert-butyl methyl ether. The suspension was concentrated to about 12 L, cooled to 0° C., and filtered. The wetcake was washed with chilled (0° C.) isopropanol (7 kg) and dried in a vacuum oven with a nitrogen purge at 60° C. to provide 2.34 kg (82%) of the desired product. MS m/z 241 (M+H)+; 1H NMR δ 8.53 (m, 1H), 7.68 (m, 1H), 7.57 (m, 1H), 7.30 (m, 1H), 7.15 (m, 1H), 7.06 (m, 1H); Anal. calcd for C9H6BrNS: C, 45.01; H, 2.50; N, 5.83. Found: C, 45.14; H, 2.45; N, 5.72.

Workup

  1. filtrationfiltered
  2. washThe wetcake was washed with tert-butyl methyl ether (12.6 kg)
  3. temperaturewhile maintaining the temperature of the filtrate at 30° C. to 35° C
  4. washThe filtrate was washed with 5% Na2SO3 (21 kg) and 10% Na2CO3 (22 kg)
  5. concentrationconcentrated to about 20 L
  6. additiondiluted with isopropanol (11 kg), which
  7. customto crystallize
  8. concentrationThe suspension was concentrated to about 12 L
  9. temperaturecooled to 0° C.
  10. filtrationfiltered
  11. washThe wetcake was washed
  12. temperaturewith chilled (0° C.) isopropanol (7 kg)
  13. customdried in a vacuum oven with a nitrogen
  14. custompurge at 60° C.

Sources & evidence

ORD record
ord-2b91c82c8ad945bf82363982217ecda4
Source dataset
uspto-grants-2003_08
Patent number
US06605707B1

Reaction notes

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