Ethyl Acetate → Ethyl (E)-4-bromobut-2-enoate

Participants

Reaction Conditions

Reaction Steps

Triphenyl phosphine (295 g, 1.12 mol) and methylene chloride (665 mL) were introduced into a 3 L one-neck flask and were stirred for 10 minutes at 0° C. And then, bromine (179.3 g) dissolved in methylene chloride (665 mL) was slowly added as droplets therein for 1 hours. At this time, the temperature of the reactor was maintained to be 0° C. The reaction product was further stirred for 30 minutes after all of bromine was added. (E)-ethyl 4-hydroxybut-2-enoate (133 g, 1.02 mol) dissolved in methylene chloride (665 mL) was slowly added as droplets into the reaction mixture for 1 hours. At this time, the temperature of the reactor was also maintained to be 0° C. After all of (E)-ethyl 4-hydroxybut-2-enoate was added, the mixture was further stirred for 30 minutes at 0° C. (the reaction was confirmed with TLC, EtOAc:hexane=1:4). After washing the organic layer of the reaction product with water (900 mL×2), the organic layer was dried with anhydrous MgSO4, and then a large quantity of Ph3P═O was extracted in company with the product by filtering and concentrating the same. The triphenyl phosphine oxide was eliminated by filtering the product, after adding n-hexane (1 L) therein and stirring the same for 30 minutes with a mechanical stirrer. (E)-ethyl 4-bromobut-2-enoate of 160 g was obtained with a yield of 81.2% by concentrating the filtered solution under a decompressed condition and distillating the concentrated solution under vacuum condition.

Provenance & Evidence