Organic Syntheses, Coll. Vol. 5, p.147 (1973); Vol. 48, p.30 (1968).
Caution! Many pyrenes are carcinogens. Contact of the skin with these materials should be avoided.
In a 500-ml., three-necked, round-bottomed flask
fitted with a stirrer
, a reflux condenser
, and a dropping funnel
are placed 8.08 g. (0.040 mole) of pyrene (Note 1)
and 80 ml. of carbon tetrachloride (Note 2)
. A solution of 2.0 ml. of bromine (6.24 g., 0.039 mole) (Note 3)
in 30 ml. of carbon tetrachloride
is added dropwise over a period of 2–3 hours. The resulting orange solution is stirred overnight, washed with three 100-ml. portions of water, and dried over anhydrous calcium chloride
. The solvent is removed under reduced pressure, the pale yellow solid residue is dissolved in 10 ml. of benzene
, and the benzene
solution is treated with a small amount of activated carbon
. The filtrate is diluted with 120 ml. of absolute ethanol
, and the solution is distilled until about 80–90 ml. of solvent remains and then cooled. The bromopyrene
crystallizes as pale yellow flakes, m.p. 93–95°
. Additional material of similar melting point is obtained from the mother liquor on concentration. The total yield is 8.5–9.5 g.
) (Note 4)
. On recrystallization from benzene-alcohol
a colorless product, m.p. 94.5–95.5°
, is obtained with little loss.
Pyrene, m.p. 151–153°, obtained from Chemicals Division, Union Carbide Chemicals Corp.
, was used by the submitter. A commercial pyrene
obtained from Germany was used by the checkers.
solvent was used.
The submitter has run this preparation on 80 g. of pyrene
with no change in yield.
This procedure is described by Lock;2
a modification using a small amount of phenol
has been published.3
The patent literature discloses the use of a tertiary amine, such as pyridine
, and its combination with other solvents for the monobromination of pyrene
with elemental bromine
Brominating agents, such as N-bromosuccinimide5
have also been used.
4. Merits of the Preparation
This preparation is referenced from:
Copyright © 1921-, Organic Syntheses, Inc. All Rights Reserved