Sulfuric Acid → 3,4-Dimethoxy-2-methyl-1-oxo-1lambda~5~-pyridine

HRID 1789055Notes

Reaction equation

HRID 1789055 reaction equation
[CH3:1][O:2][C:3]1[C:4]([CH3:13])=[N+:5]([O-:12])[CH:6]=[CH:7][C:8]=1[N+]([O-])=O.[CH3:14][O-:15].[Na+].S(=O)(=O)(O)O>CO>[CH3:1][O:2][C:3]1[C:4]([CH3:13])=[N+:5]([O-:12])[CH:6]=[CH:7][C:8]=1[O:15][CH3:14]

Participants

5

Reactant 3

HCID 1118Sulfuric AcidHCID 10942334Sodium MethoxideHCID 151634563-Methoxy-2-methyl-4-nitropyridine 1-oxide

Product 1

HCID 107496473,4-Dimethoxy-2-methyl-1-oxo-1lambda~5~-pyridineYield 88%

Reagents, catalysts & solvents 1

HCID 887MethanolSolvent

Conditions

Temperature
40 °C

Procedure

4.5 g (25 mmol) of 3-methoxy-2-methyl-4-nitropyridine 1-oxide are stirred at 40° C. in 75 ml of dry methanol, after addition of 4.7 ml of 30% strength sodium methylate solution, for 16 hours. The mixture is then cooled, brought to pH 7 with concentrated sulphuric acid, filtered and concentrated completely in vacuo, the oily, reddish residue is taken up in 50 ml of toluene, the mixture is filtered again to remove insoluble constituents and the filtrate is concentrated to dryness. The yellow oily residue crystallises in an ice-bath and is finally extracted by stirring with 30 ml of petroleum ether (50/70) at 40° C. Filtration and drying in a desiccator gives 5.2 g (88% of theory) of 3,4-dimethoxy-2-methylpyridine 1-oxide in the form of pale yellow crystals of m.p. 111°-113° C.

Workup

  1. temperatureThe mixture is then cooled
  2. filtrationfiltered
  3. concentrationconcentrated completely in vacuo
  4. filtrationthe mixture is filtered again
  5. customto remove insoluble constituents
  6. concentrationthe filtrate is concentrated to dryness
  7. customThe yellow oily residue crystallises in an ice-bath
  8. extractionis finally extracted
  9. filtrationFiltration
  10. customdrying in a desiccator

Sources & evidence

ORD record
ord-7c86e719293c4a85964d03812b201ded
Source dataset
uspto-grants-1987_08
Patent number
US04686230

Reaction notes

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