ChemicalBook CAS DataBase List 3,6-Dibromopyridazide

3,6-Dibromopyridazide synthesis

7synthesis methods

Product Name:3,6-Dibromopyridazide
CAS Number:17973-86-3
Molecular formula:C4H2Br2N2
Molecular Weight:237.88

3,6-dibromopyridazine for Synthesis: A mixture of maleic hydrazide (1.1 g, 10 mmol) and PBr5 (4.7 g, 11 mmol) was heated at 100 °C until no more white fumes of hydrogen bromide were produced (~2 h). After cooling, the orange residue was poured into ice water and the resulting mixture was extracted with CH2Cl2 (3 x 20 mL). The organic layer was washed with saturated aqueous NaHCO3, dried over MgSO4, filtered and concentrated. The crude product was purified by flash column chromatography on silica gel (CH2Cl2) to give 3,6-dibromopyridazine as a white solid (1.20 g, 50%).

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17973-86-3
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Yield:-

Reaction Conditions:

with ammonium hydroxide;phosphorus tribromide;PBr₅;bromine

Steps:

R.60 Reference Example 60

Reference Example 60 3,6-dibromopyridazine. To a cooled solution (0° C.) of phosphorus tribromide (15.7 mL, 165 mmol) is added dropwise bromine (8.5 mL, 165 mmol). The resulting solid is allowed to stand for 10 min then quickly mixed thoroughly with a spatula. To the solid PBr₅ is added 3,6-dihydroxypyridazine (16.8 g, 150 mmol), the solids mixed thoroughly and the flask equipped with a condenser and drying tube. The mixture is heated to 100° C. for 3 hours then cooled to 20° C. The solids are transferred in small portions to a cooled (-5° C.) 2N NH₄OH soln (200 mL). Collected solids by filtration and washed with cold (-5° C.) 1N NaOH (120 mL) then with H₂O till neutral pH. Dissolved solids in ether, dried over MgSO₄, concentrated and dried under high vacuum to give 25.8 g of title compound as a pale yellow solid. ¹H NMR (DMSO) δ 8.01 (s, 2H). MS (EI) m/z 236/238/240 (M⁺), Br₂.

References:

US6541505,2003,B1