Phosphorus oxychloride → 3,4,5-Trichloropyridazine

HRID 77308

Reaction equation

HRID 77308 reaction equation
[Cl:1][C:2]1[C:3](=O)[NH:4][N:5]=[CH:6][C:7]=1[Cl:8].P(Cl)(Cl)([Cl:12])=O>>[Cl:12][C:3]1[N:4]=[N:5][CH:6]=[C:7]([Cl:8])[C:2]=1[Cl:1]

Participants

3

Reactant 2

HCID 24813Phosphorus oxychlorideHCID 732474,5-Dichloro-3-hydroxypyridazine

Product 1

HCID 701113,4,5-TrichloropyridazineYield 83%

Procedure

A solution of 4,5-dichloropyridazin-3(2H)-one (2 g, 12 mmol) in 20 mL of phosphoryl trichloride was heated to reflux for 2 hrs. The solvent was removed under reduce pressure. The residue was poured into water with stirring and extracted with dichloromathene (50 mL*3). The organic layer was washed with brine, dried over Na2SO4, evaporated to give the crude product (U.S. Pat. Appl. Publ. U.S. Pat. No. 6,800,758 (Egis Gyogyszergyar Rt., Hung., Oct. 5, 2004). The crude product was recrystallized with acetone/water to give the product (2 g, 83%). 1H NMR (300 MHz, CDCl3): 9.09 (s, 1H); LC-MS: m/z=182.9 [M+H]+.

Workup

  1. temperatureto reflux for 2 hrs
  2. customThe solvent was removed
  3. additionThe residue was poured into water
  4. extractionextracted with dichloromathene (50 mL*3)
  5. washThe organic layer was washed with brine
  6. dry with materialdried over Na2SO4
  7. customevaporated
  8. customto give the crude product (U.S
  9. customThe crude product was recrystallized with acetone/water

Sources & evidence

ORD record
ord-c5684713ea704e8b9850b608e95e70a9
Source dataset
uspto-grants-2014_09
Patent number
US08841287B2

Linked notes

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