Reaktion #347568

Reaktionsgleichung

3-amino-2-methylbenzoic acid

sulfuric acid

sodium nitrite

sulfuric acid

→

desired subtitled compound

2-Methyl-3-hydroxybenzoic acid

Lösungsmittel

water

water

Reaktionsbedingungen

Aufarbeitung

1. 1
   Temperaturwhile maintaining the temperature below 7° C
2. 2
   SonstigeThe resultant reaction mixture
3. 3
   Temperaturslowly heated to 80° C. (heavy gas evolution
4. 4
   Sonstigeoccurs between the temperatures of 40°-60° C.
5. 5
   Temperaturthe reaction mixture was cooled to room temperature
6. 6
   Extraktionthe subtitled compound was extracted five times with ethyl acetate (600 mL)
7. 7
   SonstigeThe resultant layers were separated
8. 8
   ExtraktionThe titled compound was then extracted
9. 9
   Waschenthe combined organic phases were washed with brine
10. 10
    Trocknendried over sodium sulfate
11. 11
    Filtrationfiltered
12. 12
    Einengenconcentrated under reduced pressure
13. 13
    Sonstigeto provide a crude material

Vorschrift

Alternatively, the desired subtitled compound was prepared by adding 22.6 g (0.33 mol) of sodium nitrite in small portions to a cooled (-10° C.) solution of 45 g (0.30 mol) of 3-amino-2-methylbenzoic acid and 106 g (58 mL; 1.08 mol) of concentrated sulfuric acid in 400 mL of water, while maintaining the temperature below 7° C. The resultant reaction mixture was stirred for approximately 30 minutes at -10° C., poured into a solution of 240 mL of concentrated sulfuric acid in 1.2 L water, and then slowly heated to 80° C. (heavy gas evolution occurs between the temperatures of 40°-60° C.). When the gas evolution stopped, the reaction mixture was cooled to room temperature and the subtitled compound was extracted five times with ethyl acetate (600 mL). The combined organic phases were combined with 500 mL of an aqueous saturated sodium carbonate solution. The resultant layers were separated and the aqueous layer was acidified to pH 2 with concentrated hydrochloric acid. The titled compound was then extracted using ethyl acetate (500 mL) and the combined organic phases were washed with brine, dried over sodium sulfate, filtered and then concentrated under reduced pressure to provide a crude material. This material was purified using two recrystallizations from an ethyl acetate/chloroform mixture to provide 23.2 g of a light orange powder. Yield: 52%.

Quelle