Hydrochloric Acid → 4-Oxo-3-phenyl-4H-pyrido[2,1-a]phthalazine-1-carboxylic acid
Reaction equation
[O:1]=[C:2]1[N:7]2[N:8]=[CH:9][C:10]3[C:15]([C:6]2=[C:5]([C:16]([O:18]C)=[O:17])[CH:4]=[C:3]1[C:20]1[CH:25]=[CH:24][CH:23]=[CH:22][CH:21]=1)=[CH:14][CH:13]=[CH:12][CH:11]=3.[OH-].[K+].Cl>C(O)C.O>[O:1]=[C:2]1[N:7]2[N:8]=[CH:9][C:10]3[C:15]([C:6]2=[C:5]([C:16]([OH:18])=[O:17])[CH:4]=[C:3]1[C:20]1[CH:25]=[CH:24][CH:23]=[CH:22][CH:21]=1)=[CH:14][CH:13]=[CH:12][CH:11]=3Participants
Procedure
11 g of methyl 4-oxo-3-phenyl-4H-pyrido[2,1-a]phthalazine-1-carboxylate are taken up in 300 ml of ethanol, whereupon a solution of 3.7 g of potassium hydroxide in 30 ml of water is added thereto and the mixture is heated under reflux until the reaction has finished. The reaction mixture is then cooled to room temperature and poured into 2200 ml of water. The mixture is adjusted to pH 7 by adding 1N aqueous hydrochloric acid and impurities are removed by two-fold extraction with 300 ml of methylene chloride each time. The aqueous phase is acidified to pH 1 with 2N aqueous hydrochloric acid and the crystals formed are filtered off under suction. After repeated washing with water and drying in vacuo there is obtained 4-oxo-3-phenyl-4H-pyrido[2,1-a]phthalazine-1-carboxylic acid as yellow crystals of m.p. 236°-237° (dec.).
Workup
- additionis added
- temperaturethe mixture is heated
- temperatureunder reflux until the reaction
- customare removed by two-fold extraction with 300 ml of methylene chloride each time
- customthe crystals formed
- filtrationare filtered off under suction
- washAfter repeated washing with water
- customdrying in vacuo
Sources & evidence
- ORD record
- ord-1a0fe3a0bf42447f91cb5a6bec6f3ad9
- Source dataset
- uspto-grants-1989_08
- Patent number
- US04855297
Reaction notes
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