反应详情

A mixture of 116 g (0.4468 mole) of ethyl 2-chloro-4-trifluoromethyl-5-thiazolecarboxylate, 18 g (0.45 mole) of sodium hydroxide, 200 ml. of water, 400 ml. of tetrahydrofuran was stirred at room temperature for 16 hours and made acidic with 50 ml. of concentrated hydrochloric acid. The reaction mixture was extracted twice with 200 ml. of ether. The ether-tetrahydrofuran solution was dired (MgSO4) and concentrated under reduced pressure. The residual oil was treated with benzene and the benzene solution was concentrated under reduced pressure to remove the last trace of water. The residual solid was recrystallized from hexane-benzene to give 76 g (73.4%) of 2-chloro-4-trifluoromethyl-5-thiazolecarboxylic acid, m.p. 131°-131.5° C.

1. extractionThe reaction mixture was extracted twice with 200 ml
2. concentrationconcentrated under reduced pressure
3. additionThe residual oil was treated with benzene
4. concentrationthe benzene solution was concentrated under reduced pressure
5. customto remove the last trace of water
6. customThe residual solid was recrystallized from hexane-benzene