Reaktion #49629
ord-93fc24620c104a2c9d3ba2a8256382e3
Reaktionsgleichung
Edukte
Reagenzien
Reaktionsbedingungen
Aufarbeitung
- 1Temperaturcooling to 0° C. in an ice bath
- 2workup.STIRRINGwhile stirring
- 3workup.STIRRINGwith stir bar
- 4Sonstigedid not exceed 5° C
- 5SonstigeThe resultant mixture was partitioned between ether and water
- 6WaschenThe ether layer was washed with dilute aqueous NaOH
- 7Extraktionto extract any remaining product as Na salt
- 8Sonstigeto precipitate the benzoic acid
- 9ExtraktionThe resulting acid was extracted with ether
- 10WaschenThe ether layer was washed with water a few times
- 11Trocknendried with MgSO4
- 12Filtrationfiltered
- 13SonstigeRotary evaporation of the ether fraction
Vorschrift
3-fluoro-4-methoxyacetophenone (11.5 g) was dissolved in 100 ml dioxane and NaOBr solution (as prepared below) was added dropwise, with constant stirring with a stir bar at room temperature. The NaOBr solution was prepared by dissolving 40 g of NaOH in 500 ml of water, cooling to 0° C. in an ice bath, and adding bromine (12.5 ml) dropwise while stirring with stir bar; bromine was added slowly so that the reaction mixture did not exceed 5° C. After overnight stirring of the 3-fluoro-4-methoxyacetophenone, dioxane and NaOBr solution, the reaction mixture was diluted with water (200 ml). Since the reaction mixture was basic, the product, benzoic acid, was in water as its sodium salt. The resultant mixture was partitioned between ether and water. The ether layer was washed with dilute aqueous NaOH to extract any remaining product as Na salt. The aqueous layers were combined and acidified to pH 1 to precipitate the benzoic acid. The resulting acid was extracted with ether. The ether layer was washed with water a few times, dried with MgSO4, and filtered. Rotary evaporation of the ether fraction afforded 3-fluoro-4-methoxybenzoic acid (IV) in 85% yield.