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Org. Synth. 1929, 9, 20
DOI: 10.15227/orgsyn.009.0020
p-BROMOPHENACYL BROMIDE
[Acetophenone, α, p-dibromo-]
Submitted by W. D. Langley
Checked by H. T. Clarke and P. W. Boutwell.
1. Procedure
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).
2. Notes
1. A further quantity of less pure material may be obtained from the mother liquor from the recrystallization. If the acetic acid mother liquor is treated with water until turbid and then chilled, 4–5 g. of yellow crystals may be obtained. The material recovered from both liquors (6–8 g. in all) cannot be obtained in a perfectly colorless condition but the melting point is correct after recrystallization from alcohol.
2. Judefind and Reid1 have shown that many acids may be identified by conversion into their p-bromophenacyl esters by the action of p-bromophenacyl bromide on the sodium salts.
3. Discussion
p-Bromophenacyl bromide can be prepared by the interaction of bromobenzene and bromoacetyl chloride in the presence of aluminum chloride,2 and by the bromination of p-bromoacetophenone.1, 3

References and Notes
  1. Judefind and Reid, J. Am. Chem. Soc. 42, 1045 (1920).
  2. Collet, Compt. rend. 125, 717 (1897).
  3. Collet, Bull. soc. chim. (3) 21, 67 (1899).

Appendix
Chemical Abstracts Nomenclature (Collective Index Number);
(Registry Number)

p-bromophenacyl esters

ethyl alcohol (64-17-5)

acetic acid (64-19-7)

bromine (7726-95-6)

Acetophenone (98-86-2)

aluminum chloride (3495-54-3)

bromobenzene (108-86-1)

bromoacetyl chloride (22118-09-8)

p-Bromophenacyl bromide (99-73-0)

p-Bromoacetophenone (99-90-1)