Hydrazine hydrate (1:1) → 5-amino-1(2H)-phthalazinone

HRID 838973Notes

Reaction equation

HRID 838973 reaction equation
O[CH:2]1[C:11]2[C:6](=[CH:7][CH:8]=[CH:9][C:10]=2[N+:12]([O-])=O)[C:4](=O)[O:3]1.O.[NH2:16][NH2:17]>C(O)C.[Pd]>[CH4:2].[NH2:12][C:10]1[CH:9]=[CH:8][CH:7]=[C:6]2[C:11]=1[CH:2]=[N:16][NH:17][C:4]2=[O:3]

Participants

6

Reactant 2

HCID 24654Hydrazine hydrate (1:1)2×HCID 110955283-hydroxy-4-nitro-3H-isobenzofuran-1-one

Product 2

HCID 297MethaneHCID 123410025-amino-1(2H)-phthalazinoneYield 35%

Reagents, catalysts & solvents 2

HCID 23938PalladiumCatalystHCID 702EthanolSolvent2×

Procedure

A stirred solution of 3-hydroxy-4-nitrophthalide (43.4 g, 0.22 mole) and hydrazine hydrate (11.6 ml) in ethanol (1830 ml) was heated under reflux for 1 hour. The heating was discontinued and palladium on carbon (10%, 2.44 g) was added (with caution) over 15 minutes. A solution of hydrazine hydrate (24.2 ml) in ethanol (304 ml) was then added, dropwise, over 30 minutes and the mixture was heated under reflux for a further 2.5 hours. Filtration of the hot reaction mixture followed by the addition of a saturated solution of hydrogen chloride in ethanol (80 ml) to the filtrate gave a solid precipitate which was collected and washed with ethanol and ether. Evaporation of the filtrate gave a solid residue which was washed several times with boiling ethanol. The combined solids were recrystallised from water, after charcoal treatment, to give 5-amino-1(2H)-phthalazinone (12.7 g, 35%, m.p. 289°-291°).

Workup

  1. temperatureunder reflux for 1 hour
  2. temperaturethe mixture was heated
  3. temperatureunder reflux for a further 2.5 hours
  4. filtrationFiltration of the hot reaction mixture
  5. additionfollowed by the addition of a saturated solution of hydrogen chloride in ethanol (80 ml) to the filtrate
  6. customgave a solid precipitate which
  7. customwas collected
  8. washwashed with ethanol and ether
  9. customEvaporation of the filtrate
  10. customgave a solid residue which
  11. washwas washed several times with boiling ethanol
  12. customThe combined solids were recrystallised from water

Sources & evidence

ORD record
ord-d33471de1fad43308040f87c3169361c
Source dataset
uspto-grants-1978_06
Patent number
US04093725

Reaction notes

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