Hydrogen Peroxide → 3-Methyl-1-oxo-5,6,7,8-tetrahydro-1lambda~5~-quinoline

Temperature

80 °C

3-Methyl-5,6,7,8-tetrahydroquinoline (50 g.) was dissolved in glacial acetic acid (180 ml.) and the solution treated with 30% hydrogen peroxide (70 ml.) and heated at 80° C for 20 hours. The solvent was removed in vacuo and the residual oil diluted with water (25 ml.) and re-evaporated. The resulting oil was dissolved in chloroform (100 ml.), washed with aqueous sodium carbonate (2 × 25 ml.), saturated brine (2 × 25 ml.), dried (MgSO4) and the solvent removed in vacuo to give 3-Methyl-5,6,7,8-tetrahydroquinoline-1-oxide (60 g.) as a pale yellow solid which was used without purification. The N-oxide (60 g.) was dissolved in acetic anhydride (120 ml.) and added to boiling acetic anhydride (120 ml.) and the mixture heated at reflux for 30 minutes. The solvent was removed in vacuo and the residual oil was treated with 10% hydrochloric acid (700 ml.) and the solution heated on a steam bath for 2 hours. The cooled reaction mixture was adjusted to pH 9.0 with sodium hydroxide and extracted with ether (3 × 100 ml.). The combined ethereal extracts were washed with saturated brine, dried (MgSO4) and the solvent removed in vacuo. The resultant oil was distilled at 0.15 mmHg to give a colourless oil (22 g.) b.p. 70°-78° C which crystallised from n-hexane to give 8-hydroxy-3-methyl-5,6,7,8-tetrahydroquinoline as colourless needles m.p. 58° C.

1. customThe solvent was removed in vacuo
2. additionthe residual oil diluted with water (25 ml.)
3. customre-evaporated
4. dissolutionThe resulting oil was dissolved in chloroform (100 ml.)
5. washwashed with aqueous sodium carbonate (2 × 25 ml.), saturated brine (2 × 25 ml.)
6. dry with materialdried (MgSO4)
7. customthe solvent removed in vacuo

ORD record

ord-85f538a45ce34281a9a112386a84c1ed

Source dataset

uspto-grants-1977_09

DOI

10.6084/m9.figshare.5104873.v1

Patent number

US04048175