Organic Syntheses, Coll. Vol. 2, p.553 (1943); Vol. 16, p.73 (1936).
In a 2-l. round-bottomed flask
equipped with a mechanical stirrer
are placed 1 l. of 2 per cent sulfuric acid
, 0.5 g. of vanadium pentoxide (Note 1)
, 110 g. (1 mole) of hydroquinone
, and 60 g. (0.56 mole) of sodium chlorate
. The mixture is vigorously stirred for about three hours, when the green quinhydrone
first formed is converted to yellow quinone
. The temperature of the reaction mixture rises to about 40° (Note 2)
. The reaction is usually complete in three and one-half to four hours. The flask is then disconnected and cooled under the tap, the mixture is filtered with suction, and the quinone
is washed once with about 100 cc. of cold water. After drying in a desiccator
over calcium chloride
, the product weighs 86–90 g.
and melts at 110–112°
. This material is pure enough for most purposes. Extraction of the filtrate and washings with four 100-cc. portions of benzene
yields a further 12–14 g.
and brings the total amount to 99–104 g.
per cent of the theoretical yield) (Note 3)
Very pure quinone
can be obtained either by vacuum sublimation or recrystallization from boiling ligroin
). One hundred grams of the crude quinone
requires about 1.2 l. of ligroin
for recrystallization and yields 92–97 g.
of bright yellow quinone
, m.p. 111–113°
If quantities larger than one mole of hydroquinone
are used the temperature should not be allowed to rise above 40°.
By the use of a suitable organic solvent the same oxidizing agent can be employed for the preparation of anthraquinone
. A mixture of 90 g. (0.51 mole) of finely powdered pure anthracene
, 0.5 g. of vanadium pentoxide
, 76 g. of sodium chlorate
, 1 l. of glacial acetic acid
, and 200 cc. of 2 per cent sulfuric acid
is warmed under reflux until a vigorous reaction commences. The source of heat is removed, and the reaction allowed to proceed for about twenty minutes. The mixture is refluxed for one hour longer and then cooled in ice. The light yellow solid is filtered with suction, washed well with water, and dried at 110°. The yield is 92–96 g.
per cent of the theoretical amount) of a product melting at 273–275°
This preparation is referenced from:
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