Phosphorus oxychloride → 3-Bromo-2,5-dichloropyridine

HRID 974227Notes

Reaction equation

HRID 974227 reaction equation
[Br:1][C:2]1[C:3](=O)[NH:4][CH:5]=[C:6]([Cl:8])[CH:7]=1.O=P(Cl)(Cl)[Cl:12]>CN(C=O)C>[Br:1][C:2]1[C:3]([Cl:12])=[N:4][CH:5]=[C:6]([Cl:8])[CH:7]=1

Participants

4

Reactant 2

HCID 24813Phosphorus oxychlorideHCID 27267913-Bromo-5-chloropyridin-2-ol

Product 1

HCID 129015963-Bromo-2,5-dichloropyridineYield 89.2%

Reagents, catalysts & solvents 1

HCID 6228DimethylformamideSolvent

Conditions

Temperature
70 °C

Procedure

To a solution of 3-bromo-5-chloropyridin-2-one (84.3 g, 0.404 mol) in DMF (100 mL) was added POCl3 (56.5 mL, 0.61 mol) via dropping funnel over 3 hours at room temperature. The resulting black solution was then heated to 70° C. and allowed to stir for 3 days. After cooling to room temperature, the solution was poured into 1 L of ice/water, filtered, and the solid dried in a vacuum oven to provide 81.76 g (89%) of the desired 3-bromo-2,5-dichloropyridine as an off-white solid, m.p. 39-41° C.: IR(CHCl3) 3867, 3663, 2989, 2734, 1812, 1606, 1547, 1400, 1366, 1230, 1155, 1129, 1074, 1027, 894, 658, 563 cm-1 ; 1H NMR (300 MHz, CDCl3) δ 8.0 (d, 1H, J=2.2 Hz), 8.35 (d, 1H, J=2.2 Hz); 13C NMR (CDCl3) δ 120.43, 130.74, 141.46, 146.64, 148.99; exact mass calculated for C5H2NBrCl2 =224.8748; high resolution mass spec. 224.8764.

Workup

  1. customover 3 hours
  2. customat room temperature
  3. temperatureAfter cooling to room temperature
  4. filtrationfiltered
  5. customthe solid dried in a vacuum oven

Sources & evidence

ORD record
ord-3c88f6db42ef4985b7b290c84f68aaa2
Source dataset
uspto-grants-1991_11
Patent number
US05068333

Reaction notes

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