Organic Syntheses, Coll. Vol. 4, p.895 (1963); Vol. 34, p.90 (1954).
In a 1-l. round-bottomed three-necked flask
, equipped with a thermometer
, a reflux condenser
, and two fritted-glass gas dispersion tubes (Note 1)
, is placed 600 g. (4.54 moles) of pure tetralin (Note 2)
. The flask is placed in a constant-temperature bath at 70°, and a finely dispersed stream of oxygen
is passed through the tetralin
until the peroxide
content of the reaction mixture is 25–30% as shown by an active oxygen
content of 2.4–2.9% (Note 3)
. This oxidation requires 24–48 hours. The reaction mixture is then distilled (Note 4)
in an all-glass apparatus at 0.2–0.4 mm. through a 60 by 2.5 cm. Vigreux column
, until a pot temperature of 70° is reached. About 370–380 g. of unoxidized tetralin
, boiling at 32–45°/0.2–0.4 mm.
, is recovered. The pot residue is a slightly viscous amber-colored oil which weighs 225–235 g.
and consists of about 80% tetralin hydroperoxide (Note 5)
. To obtain the pure hydroperoxide
the residue is dissolved in 450 ml. of toluene
and the solution is cooled to −50° with stirring (Note 6)
. After standing at −50° for 1 hour, the slurry is separated by suction filtration (Note 7)
and the precipitate is dried at room temperature at 1–2 mm. There is thus obtained 120–125 g.
of moderately pure tetralin hydroperoxide
, m.p. 50.2–52.0°
, active oxygen
content 9.20% (Note 8)
. Recrystallization from 480 ml. of toluene
at −30° yields 80–85 g.
yield based on the peroxide
content of the oxidized tetralin
) of pure tetralin hydroperoxide
as a colorless solid, m.p. 54.0–54.5°
, active oxygen
content, 9.70% (Note 9)
Rubber connections must be avoided because rubber is rapidly attacked by tetralin
. Convenient gas dispersion tubes are Pyrex No. 39533.
Pure tetralin was prepared from the practical grade supplied by the Eastman Kodak Company
by the procedure of George and Robertson:2
Three kilograms was fractionally distilled through a packed column, the fraction boiling at 204–207° being retained (2.7 kg.). This was gently shaken with 1 lb. of mercury
, and the upper layer was carefully decanted through fluted filter
paper. The crude tetralin
was next shaken with saturated aqueous mercuric acetate
solution, and the aqueous layer and a small amount of orange precipitate were discarded. The hydrocarbon was then shaken with 5 successive 300-ml. portions of concentrated sulfuric acid
, once with 10% sodium hydroxide
, and finally with water until the washings were neutral. The tetralin
was dried over anhydrous calcium chloride
and distilled through a packed column in a nitrogen
atmosphere. In this way, 2 kg.
of pure tetralin
was obtained, b.p. 206–207°
content is determined iodometrically:3
In an iodine
flask, an accurately weighed sample (0.1–0.3 g.) is dissolved in 20 ml. of an acetic acid-chloroform
solution (3:2 by volume), and 2 ml. of saturated aqueous potassium iodide
solution is added. The flask is immediately flushed with nitrogen
, stoppered, and allowed to stand at room temperature for 15 minutes. Fifty milliliters of water is then added with good mixing, and the liberated iodine
is titrated with 0.1N sodium thiosulfate
, employing starch as indicator. A blank titration, which usually does not exceed 0.2 ml., is also run. One milliliter of 0.1N sodium thiosulfate
is equivalent to 0.00821 g. of tetralin hydroperoxide
The distillation should be conducted behind a safety shield.
loss up to this point is negligible provided an all-glass apparatus has been used throughout and the distillation temperature has not exceeded 70°.
A Dry Ice-ethanol bath
is convenient for cooling the solution.
Filtration may be carried out in a suction funnel
surrounded by a Dry Ice-ethanol cooling bath, or using a cold box maintained at −50°.
is a convenient model compound for many studies in peroxide
chemistry. It remains colorless and does not decrease in peroxide
content for months if stored in the dark at or below 0°. Storage under warm summer conditions for several months results in decomposition to a dark, viscous liquid.
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