5-Methylhex-3-en-2-one → 3-Bromo-5-methyl-3-hexen-2-one

Participants

Reaction Steps

A solution of 84 g of bromine in 75 ml of CCl4 was added dropwise to a mixture of 42 g of NaHCO3 and 56 g of 5-methyl-3-hexen-2-one in 175 ml of CCl4 at 0° C. while stirring in the course of 2 hours. The reaction mixture was stirred for a further hour at 0° C. and then filtered off and evaporated down. The residue was taken up in 150 ml of a 1:1 mixture of ethanol and water, to which 63 g of NaHCO3 had been added. The mixture was heated to reflux while stirring for 2 hours. After cooling, it was poured out into ice-water. This mixture was extracted three times with pentane. This extract was washed twice with water, dried over MgSO4, filtered off and evaporated down. The residue was distilled, 41 g of 3-bromo-5-methyl-3-hexen-2-one (E) being obtained, b.p. 62°-82° C./2 kPa.

Provenance & Evidence