Acetic Anhydride → 4-(Trifluoromethyl)dihydro-2H-pyran-2,6(3H)-dione

Into a 2 liter 3-necked flask equipped with a mechanical stirrer and reflux condenser were added 320 g (1.6 mol) 3-(trifluoromethyl)glutaric acid and 775 ml acetic anhydride. The solution was refluxed for 2.5 hours and allowed to cool to room temperature. The majority of the acetic anhydride was removed in vacuo (80° C.) to afford a brown solid which was dissolved in 800 ml of CHCl3 on a steam bath. Following the addition of 200 ml hexanes, a white precipitate began to form. Further crystallization was induced by storage in a refrigerator. The white flocculent solid was filtered and oven dried (50° C., 30 mm Hg) to afford 261 g (89% yield) of the desired product, m.p. 88°-91° C.

1. customInto a 2 liter 3-necked flask equipped with a mechanical stirrer
2. temperaturereflux condenser
3. temperatureThe solution was refluxed for 2.5 hours
4. customThe majority of the acetic anhydride was removed in vacuo (80° C.)
5. customto afford a brown solid which
6. customto form
7. customFurther crystallization
8. filtrationThe white flocculent solid was filtered
9. customoven dried (50° C., 30 mm Hg)

ORD record

ord-f81f5a593c1b4936beb55394732342d6

Source dataset

uspto-grants-1993_08

DOI

10.6084/m9.figshare.5104873.v1

Patent number

US05238908