In a
500-cc. flask are placed
50 g. (0.25 mole) of p-bromoacetophenone (p. 109) and
100 cc. of glacial acetic acid. To the resulting solution is very slowly added
40 g. (12.5 cc., 0.25 mole) of bromine, keeping the temperature below 20°. The mixture is vigorously shaken by hand during the addition.
p-Bromophenacyl bromide begins to separate as needles when about one-half of the
bromine has been added. The addition requires about thirty minutes.
When all the
bromine has been added, the flask is cooled in ice-water and the product filtered with suction. The crude crystals are washed with
50 per cent ethyl alcohol until colorless (about 100 cc. is required). The material so obtained, when air-dried, melts at
106–108° and weighs
55–60 g. It is recrystallized from
400 cc. of 95 per cent ethyl alcohol, from which it separates as colorless needles melting at
108–109°. The yield is
48–50 g. (
69–72 per cent of the theoretical amount) (Note
1).