Hydrochloric Acid → 2-Chloro-4-(trifluoromethyl)-1,3-thiazole-5-carboxylic acid

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 dried (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. dry with materialThe ether-tetrahydrofuran solution was dried (MgSO4)
3. concentrationconcentrated under reduced pressure
4. additionThe residual oil was treated with benzene
5. concentrationthe benzene solution was concentrated under reduced pressure
6. customto remove the last trace of water
7. customThe residual solid was recrystallized from hexane-benzene

ORD-Eintrag

ord-dd2116f579084af3ba15d6756a9763cb

Quelldatensatz

uspto-grants-1986_07

DOI

10.6084/m9.figshare.5104873.v1

Patentnummer

US04602937