Hydrochloric Acid → 3-hydroxy-2-methyl-4H-1-benzopyran-4-one

HRID 1282250Notes

Reaction equation

HRID 1282250 reaction equation
[CH3:1][CH:2]1[CH2:7][C:6](=[O:8])[C:5]2[CH:9]=[CH:10][CH:11]=[CH:12][C:4]=2[O:3]1.C([O:18]N=O)CC(C)C.Cl.O>C(O)C.C(Cl)(Cl)Cl>[OH:18][C:7]1[C:6](=[O:8])[C:5]2[CH:9]=[CH:10][CH:11]=[CH:12][C:4]=2[O:3][C:2]=1[CH3:1]

Participants

7

Reactant 4

HCID 313Hydrochloric AcidHCID 962WaterHCID 8053Isoamyl NitriteHCID 380147HCID 380147, compound

Product 1

HCID 103749433-hydroxy-2-methyl-4H-1-benzopyran-4-oneYield 51%

Reagents, catalysts & solvents 2

HCID 702EthanolSolventHCID 6212ChloroformSolvent

Procedure

2,3-dihydro-2-methyl-4H-1-benzopyran-4-one (1.62 g) is dissolved in ethanol 95% (50 ml) and the solution is refluxed under stirring. In 10-15 minutes isoamylnitrite (8 ml) and concentrated HCl (40 ml) are added drop by drop. Heating and stirring are stopped, and the resulting mixture is allowed to stand ca. 2 hours. Then water (200 ml) is added until precipitation of a white solid. The solvent is evaporated, obtaining a solid product which is dissolved in a little volume of chloroform and purified on silica gel in equilibrium with the same solvent. The purified product contains a low percentage of yellow impurities which can be completely eliminated by crystallisation in acetone. The residual solvent is then eliminated, obtaining 0.97 g of 3-hydroxy-2-methyl-4H-1-benzopyran-4-one (colourless crystals; m.p.=179-180° C.; IR: 1632, 1666 e 3301 cm−1; yield=51%).

Workup

  1. temperaturethe solution is refluxed
  2. temperatureHeating
  3. stirringstirring
  4. customThe solvent is evaporated
  5. customobtaining a solid product which
  6. custompurified on silica gel in equilibrium with the same solvent
  7. customcan be completely eliminated by crystallisation in acetone

Sources & evidence

ORD record
ord-0fabdd36f6de4fd68d4bb3101662d1b3
Source dataset
uspto-grants-2002_09
Patent number
US06455578B1

Reaction notes

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