Sodium Hydroxide → 2-Methoxyimino-3-oxobutyric acid

Temperature

4 °C

A mixture of ethyl 2-methoxyimino-3-oxo-butyrate, syn isomer (52 g), ethanol (300 cc) and 1 N sodium hydroxide solution (330 cc) is heated under reflux for 15 hours. The mixture is concentrated by evaporation of ethanol at 20° C. under a pressure of 20 mm Hg (2.7 kPa) and is then extracted with methylene chloride (150 cc). The aqueous phase is treated with animal charcoal (1 g), filtered, saturated with sodium chloride, cooled to 4° C. and acidified to pH2 with 2 N hydrochloric acid in the presence of methylene chloride (200 cc). It is then re-extracted with the same solvent (2×100 cc), followed by ethyl acetate (6×200 cc). The organic phases are dried over sodium sulphate and concentrated to dryness separately at 20° C. under 20 mm Hg (2.7 kPa). The residues are combined and treated with isopropyl ether (80 cc) for 4 hours, with very vigorous stirring. The crystals obtained are filtered off and dried, and 2-methoxyimino-3-oxo-butyric acid, syn isomer (8.9 g) is thus obtained.

1. temperatureis heated
2. temperatureunder reflux for 15 hours
3. concentrationThe mixture is concentrated by evaporation of ethanol at 20° C. under a pressure of 20 mm Hg (2.7 kPa)
4. extractionis then extracted with methylene chloride (150 cc)
5. additionThe aqueous phase is treated with animal charcoal (1 g)
6. filtrationfiltered, saturated with sodium chloride
7. extractionIt is then re-extracted with the same solvent (2×100 cc)
8. dry with materialThe organic phases are dried over sodium sulphate
9. concentrationconcentrated to dryness separately at 20° C. under 20 mm Hg (2.7 kPa)
10. additiontreated with isopropyl ether (80 cc) for 4 hours, with very vigorous stirring
11. customThe crystals obtained
12. filtrationare filtered off
13. customdried

ORD record

ord-55c0ef5d17f2404b983068327bb59190

Source dataset

uspto-grants-1981_12

DOI

10.6084/m9.figshare.5104873.v1

Patent number

US04307233