Pyridazine, 3,6-dione, 4-bromo-1,2-dihydro- synthesis
- Product Name:Pyridazine, 3,6-dione, 4-bromo-1,2-dihydro-
- CAS Number:15456-86-7
- Molecular formula:C4H3BrN2O2
- Molecular Weight:190.98
5926-51-2
15456-86-7
The general procedure for the synthesis of 4-bromo-3,6-pyridazinedione from bromomaleic anhydride was as follows: hydrazine sulfate (2.25 g, 17.2 mmol) was dissolved in boiling water (20 mL) under stirring conditions. Bromomaleic anhydride (2.6 mL, 28.2 mmol) was added dropwise to this solution through an addition funnel. The reaction mixture was heated under reflux conditions (100 °C) for 19 h and subsequently cooled to room temperature. The reaction mixture was filtered through a medium glass material sintered glass funnel and a white precipitate was collected. The precipitate was washed with acetone (3 x 5 mL) and then dried under vacuum to afford the target product 4-bromo-1,2-dihydropyridazine-3,6-dione (2.85 g) as a white powder in 87% yield (based on gravimetric analysis) with a melting point of 262°C.
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15456-86-7
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Yield:-
Reaction Conditions:
in water
Steps:
10.A (a)
The reaction was repeated with 29 g hydrazine sulphate, 53 g bromomaleic anhydride and 130ml water. The precipitates were collected by filtration, washed with water and acetone and dried as a combined batch in vacuo to afford 4-bromo-1,2-dihydro-3,6-pyridazinedione as a white solid (113 g). The solid in two batches was treated with phosphorus oxychloride (2 x 200 ml) and heated to reflux for 3.5 hours. The mixture was cooled, evaporated and azeotroped with toluene. The residue was partitioned between dichloromethane and saturated aqueous sodium bicarbonate solution and extracted with DCM twice more. The organic extracts were dried and evaporated. This residue was re-dissolved in dichloromethane, and chromatographed on silica gel (300 g) (DCM as eluent) to give a white solid (101.5 g, 87%). (LC/MS analysis showed ca 20-30% impurity, isomers of bromo-dichloropyridazine). MS (+ve ion electrospray) m/z 184/185/186 (MH+), trichloropyridazine MS (+ve ion electrospray) m/z 228/229/231 (MH+), bromo-dichloropyridazine.
References:
GLAXO GROUP LIMITED EP1980251, 2008, A1
5926-51-2
102 suppliers
$10.00/250mg
15456-86-7
91 suppliers
$9.00/250mg