Reaction #47514

Reaction equation

(E)-3-(2,5-dichloro-phenoxy)-but-2-enoic acid ethyl ester

N-bromosuccinimide

benzoyl peroxide

→

(E)-4-bromo-3-(2,5-dichloro-phenoxy)-but-2-enoic acid ethyl ester

Yield 43.0%

Solvents

carbon tetrachloride

Conditions

Workup

1. 1
   OtherNitrogen gas was bubbled through the mixture for 5 min
2. 2
   Temperaturethe resulting mixture was heated
3. 3
   Temperatureto reflux for 4 h
4. 4
   Otherwas then placed in the refrigerator overnight
5. 5
   OtherThe solids formed
6. 6
   Otherwere removed by filtration
7. 7
   Concentrationthe filtrate concentrated in vacuo
8. 8
   OtherThe crude product obtained
9. 9
   Otherwas purified

Procedure

To a stirred mixture of (E)-3-(2,5-dichloro-phenoxy)-but-2-enoic acid ethyl ester (3.25 g, 0.012 mol) in carbon tetrachloride (20 mL) under a nitrogen atmosphere was added N-bromosuccinimide (3.20 g, 0.018 mol) and benzoyl peroxide (290 mg, 0.001 mol). Nitrogen gas was bubbled through the mixture for 5 min, and the resulting mixture was heated to reflux for 4 h. The reaction mixture was then placed in the refrigerator overnight. The solids formed were removed by filtration and the filtrate concentrated in vacuo. The crude product obtained was purified using flash column chromatography (silica gel (100-200 mesh), ethyl acetate/hexanes) to afford (E)-4-bromo-3-(2,5-dichloro-phenoxy)-but-2-enoic acid ethyl ester (1.80 g, 43%) as a yellow oil.

Source