Hydrochloric Acid → 2-Bromo-3-(2-thienyl)-1-propene

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Reaction Steps

A 1000 ml 3-necked round-bottomed flask was fitted with a mechanical stirrer through a mineral oil sealed bearing, a reflux condenser and a 1000 ml addition funnel. A mixture of 70 g of 2,3-dibromopropene and 100 ml of dry ethyl ether was added. The flask was now cooled to 0° C. in acetone/dry-ice and a solution of thienyl magnesium bromide, prepared from 7.8 of magnesium 50 g of 2-bromothiophene (0.31 mol) and 260 ml of dry ether was added at such a rate so that the temperature did not exceed 38° C. The addition took about 1.5 hrs. Stirring was continued and the acetone/dry-ice bath was replaced with a heating mantle. The mixture was gently refluxed for 1.5 hrs. after which time the flask was again cooled and a solution of 5 ml of 36% hydrochloric acid and 200 g of ice were added. The contents of the flask were then transferred to a separatory funnel, and the ether layer was separated and dried over anhydrous sodium sulfate. The ether was distilled off and the residue was fractionated under reduced pressure (65°-78° C./0.5 mm) yielding 41.8 g (67 percent of theory). The residue, 26 g, consisted mainly of diphenyl, m.p. 69°-71° C.

Provenance & Evidence