Reaktion #2286279

Reaktionsgleichung

(3,5-dimethyl-4-hydroxy-phenyl)-acetic acid

sulfuric acid

methanol

→

(3,5-dimethyl-4-hydroxy-phenyl)-acetic acid methyl ester

Ausbeute 86.0%

Lösungsmittel

Reaktionsbedingungen

Aufarbeitung

1. 1
   TemperaturAt this time, the reaction was cooled to room temperature
2. 2
   EinengenThe reaction was concentrated under vacuum
3. 3
   workup.ADDITIONThe residue was diluted with ethyl acetate (700 mL)
4. 4
   Waschenwas washed with water (2×250 mL)
5. 5
   TrocknenThe organics were dried over magnesium sulfate
6. 6
   Filtrationfiltered
7. 7
   Einengenconcentrated under vacuum
8. 8
   Sonstigeto give an orange solid
9. 9
   FiltrationThe solid was collected by filtration
10. 10
    Waschenwashed with 10% ethyl acetate/petroleum ether
11. 11
    Sonstigedried under vacuum overnight
12. 12
    SonstigeThe residue was purified by column chromatography
13. 13
    Wascheneluted with 10-15% ethyl acetate in petroleum ether

Vorschrift

A solution of (3,5-dimethyl-4-hydroxy-phenyl)-acetic acid (5a) (12.4 g, 0.069 mmol) in methanol (300 mL) was treated with concentrated sulfuric acid (6.25 mL). The resulting solution was heated to 70° C. overnight. At this time, the reaction was cooled to room temperature. The reaction was concentrated under vacuum. The residue was diluted with ethyl acetate (700 mL) and was washed with water (2×250 mL). The organics were dried over magnesium sulfate, filtered and concentrated under vacuum to give an orange solid. The solid was slurried in 10% ethyl acetate/petroleum ether and was stirred for 1 h. The solid was collected by filtration, washed with 10% ethyl acetate/petroleum ether, and dried under vacuum overnight. The residue was purified by column chromatography using silica gel eluted with 10-15% ethyl acetate in petroleum ether to afford (3,5-dimethyl-4-hydroxy-phenyl)-acetic acid methyl ester (6a) (1.93 g, 86%) as an off-white solid; EI(+)-HRMS m/z calcd for C11H14O3 (M+) 194.0943, found 191.0942. Molecular Weight=194.2324; Exact Mass=194.0943

Quelle