Reaktion #10372

Reaktionsgleichung

NaHCO3

ethanol

3-methyl-2,4,5-trifluorobenzoic acid

oxalyl chloride

→

title compound

Ausbeute 77.1%

2,4,5-Trifluoro-3-methylbenzoic acid ethyl ester

Ausbeute 77.1%

Lösungsmittel

dichloromethane

Reaktionsbedingungen

Aufarbeitung

1. 1
   Einengenconcentrated
2. 2
   Sonstigedried in vacuo
3. 3
   workup.ADDITIONThe acid chloride is diluted with dichloromethane
4. 4
   Temperaturcooled to 0° C.
5. 5
   workup.STIRRINGThe resulting solution is stirred at room temperature for 20 hours
6. 6
   Extraktionextracted with dichloromethane
7. 7
   WaschenThe organic extracts are washed with brine
8. 8
   Trocknendried over Na2SO4
9. 9
   Filtrationfiltered
10. 10
    Einengenconcentrated under vacuum

Vorschrift

A solution of 3-methyl-2,4,5-trifluorobenzoic acid (Shimizu T., Asai T., Kumai S., Jpn. Kokai Tokkyo Koho (1997) Japanese Appl. JP 95-219069, 4.3 g, 22.6 mmol) in dichloromethane (100 mL) at 0° C. is treated with oxalyl chloride (4.2 g, 33 mmol) followed by N,N-dimethylformamide (2 drops). The mixture is stirred at room temperature for 3 hours, concentrated and dried in vacuo. The acid chloride is diluted with dichloromethane, cooled to 0° C., and treated with absolute ethanol (10 mL, 170 mmol). The resulting solution is stirred at room temperature for 20 hours, poured into saturated NaHCO3 solution and extracted with dichloromethane. The organic extracts are washed with brine, dried over Na2SO4, filtered, and concentrated under vacuum to afford the title compound (3.8 g). 1H NMR (200 MHz, CDCl3): δ 7.67–7.26 (m, 1H), 4.44 (q, 2H), 2.27 (dd, 3H), 1.42 (t, 3H).

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