Reaction #1175388

Reaction equation

bromine

dimethylformamide

trifluoro-5-hydroxy-2-pentanone

dimethyl formamide

→

desired product

1,1,1-Trifluoro-5-bromo-2-pentanone

Solvents

ether

Conditions

Workup

1. 1
   workup.DISTILLATIONwas distilled through a 30 cm vigreaux column at 2.0 mm of pressure
2. 2
   OtherTwo fractions were collected
3. 3
   Otherfrom 27°-35° C.
4. 4
   Otherat 35°-70° C
5. 5
   OtherThe second fraction was partitioned between water and ethyl ether
6. 6
   Washthe organic layer was washed with water (3×100 mL
7. 7
   Dryingdried (anhydrous MgSO4)
8. 8
   Otherevaporated under reduced pressure at ambient temperature
9. 9
   Otherto give

Procedure

A 500 mL three neck round bottom flask, fitted with dropping funnel, magnetic stirrer, ice-salt bath, and argon inlet is charged with 125 mL of dry dimethylformamide, 29 g(35.7 mM) of trifluoro-5-hydroxy-2-pentanone. This mixture was cooled to -5° C. and 11.5 g(71.6 mM) of bromine was added dropwise over a two hour period. After stirring overnight at ambient temperature the reaction mixture was distilled through a 30 cm vigreaux column at 2.0 mm of pressure. Two fractions were collected; the first fraction from 27°-35° C. and the second fraction at 35°-70° C. The second fraction was partitioned between water and ethyl ether, the organic layer was washed with water (3×100 mL, dried (anhydrous MgSO4), and evaporated under reduced pressure at ambient temperature to give 40 g of a colorless oil mixture of dimethyl formamide, ether, and the desired product which was used in the next reaction without further purification.

Source