Sulfuric Acid → 5-Hydroxy-1,2-dihydrophthalazin-1-one

HRID 838974Notes

Reaction equation

HRID 838974 reaction equation
S(=O)(=O)(O)O.N[C:7]1[CH:16]=[CH:15][CH:14]=[C:13]2[C:8]=1[CH:9]=[N:10][NH:11][C:12]2=[O:17].N([O-])=[O:19].[Na+].B(O)(O)O>O>[OH:19][C:7]1[CH:16]=[CH:15][CH:14]=[C:13]2[C:8]=1[CH:9]=[N:10][NH:11][C:12]2=[O:17]

Participants

6

Reactant 4

HCID 1118Sulfuric Acid2×HCID 7628Boric AcidHCID 123410025-amino-1(2H)-phthalazinoneHCID 23668193Sodium Nitrite

Product 1

HCID 1357291005-Hydroxy-1,2-dihydrophthalazin-1-oneYield 97%

Reagents, catalysts & solvents 1

HCID 962WaterSolvent3×

Procedure

Concentrated sulphuric acid (8 ml) was added to a stirred mixture of 5-amino-1(2H)-phthalazinone (9.4 g, 0.058 mole) and water (50 ml). The resultant stirred paste was cooled in ice and diazotised by the addition of sodium nitrite (4.15 g, 0.06 mole) in water (15 ml). The filtered diazonium sulphate solution was added over 1.5 hours to a stirred boiling solution of concentrated sulphuric acid (30 ml) and boric acid (5.42 g, 0.088 mole) in water (200 ml). The solution was heated for a further 30 minutes then cooled and the collected solid was washed with water to give 5-hydroxy-1(2H)-phthalazinone 9.12 g, 96% m.p. 351°-355°). 5-Hydroxy-1(2H)-phthalazinone was purified as the 5-acetoxy derivative m.p. 162° (ethanol).

Workup

  1. temperaturewas cooled in ice
  2. temperatureThe solution was heated for a further 30 minutes
  3. temperaturethen cooled
  4. washthe collected solid was washed with water

Sources & evidence

ORD record
ord-aa03621d27574beeb95979473212119c
Source dataset
uspto-grants-1978_06
Patent number
US04093725

Reaction notes

Loading…