Water → 4-Bromo-6-chloro-2,3-dihydropyridazin-3-one

HRID 572684Notes

Reaction equation

HRID 572684 reaction equation
N([O-])=O.[Na+].S(=O)(=O)(O)O.[Br:10][C:11]1[CH:16]=[C:15]([Cl:17])[N:14]=[N:13][C:12]=1N.[OH2:19]>C(O)(=O)C>[Br:10][C:11]1[C:12](=[O:19])[NH:13][N:14]=[C:15]([Cl:17])[CH:16]=1

Participants

6

Reactant 4

HCID 962WaterHCID 1118Sulfuric AcidHCID 220244193-Amino-4-bromo-6-chloropyridazineHCID 23668193Sodium Nitrite

Product 1

HCID 115865224-Bromo-6-chloro-2,3-dihydropyridazin-3-oneYield 83%

Reagents, catalysts & solvents 1

HCID 176Acetic AcidSolvent

Conditions

Temperature
20 °C

Procedure

To a cooled solution (0-5° C.) of sodium nitrite (5.96 g, 86 mmol, Lobachem) in sulfuric acid (90 mL, 57.6 mmol) was added 4-bromo-6-chloropyridazin-3-amine (12 g, 57.6 mmol, Preparation #26) in acetic acid (300 mL). The mixture was stirred for 1 hr at about 20° C. and water was added (450 mL). The reaction mixture stirred for another 5 h at RT. The reaction mixture was extracted with EtOAc (3×200 mL), dried over sodium sulphate and evaporated on rotovapor. The residue obtained was purified by silica gel column chromatography by eluting with 50% EtOAc in hexane to afford 4-bromo-6-chloropyridazin-3(2H)-one 10 g, (83%) as pale yellow solids; 1H NMR (400 MHz, DMSO) δ 13.527 (s, 1H), 8.203 (s, 1H). MS m/z: 208.8 (M−H)−,

Workup

  1. stirringThe reaction mixture stirred for another 5 h at RT
  2. extractionThe reaction mixture was extracted with EtOAc (3×200 mL)
  3. dry with materialdried over sodium sulphate
  4. customevaporated on rotovapor
  5. customThe residue obtained
  6. customwas purified by silica gel column chromatography
  7. washby eluting with 50% EtOAc in hexane

Sources & evidence

ORD record
ord-cfcaa478c1b84bce863b808b23c5e283
Source dataset
uspto-grants-2015_05
Patent number
US09029409B2

Reaction notes

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