Org. Synth. 1959, 39, 23
Submitted by Richard G. Gillis and A. B. Lacey1
Checked by B. C. McKusick and R. J. Harder.
In a 3-l. round-bottomed flask
fitted with a mechanical stirrer
and a reflux condenser
is placed 2.0 l. of anhydrous ethanol
. To this is added 11.5 g. (0.5 g. atom) of sodium
cut into small pieces. When the sodium
is completely dissolved, 23.6 g. (21.0 ml., 0.25 mole) of 1,2-ethanedithiol (p. 401)
is added, followed by 47.0 g. (21.7 ml., 0.25 mole) of ethylene dibromide
. The mixture is stirred and heated under reflux for 4 hours, cooled, and filtered to remove some sodium bromide
mixed with polyethylene sulfide
. The solid is washed with 100 ml. of ethanol
, and the combined filtrates are distilled with stirring. When bumping becomes troublesome, as it generally does when 1.3–1.5 l. of distillate has been collected, the hot reaction mixture is filtered to remove sodium bromide
, and the sodium bromide
is washed with 100 ml. of hot ethanol
The combined filtrates are returned to the reaction vessel, and distillation with stirring is continued until virtually all the ethanol
has been removed. The distillation is stopped when crystals of p-dithiane
appear in the condenser or when dilution of the distillate with water causes a milky appearance or the formation of a small quantity of crystals. One liter of water is added to the residue, and the stirred mixture is distilled, using the apparatus of Fig. 8 (Note 1)
, until no more p-dithiane
solidifies in the condenser.
Fig. 8. Apparatus for steam distillation of a solid.
The dithiane is filtered and dried over phosphorus pentoxide or sodium hydroxide in a desiccator at atmospheric pressure. It melts at 112–113° and weighs 16.5–18.1 g. (55–60%).
The apparatus illustrated is convenient for the steam distillation of compounds which solidify in the condenser. By having the water condenser vertical, it can easily be cleared with a glass rod
. No solidification occurs in the side arm, which behaves as a short air condenser. The adapter
shown need not be specially constructed but may be assembled from commercially available components; the dimensions and joint sizes are not critical.
The procedure described is essentially that of Victor Meyer.2 p-Dithiane
has also been obtained from the pyrolysis of the polymer formed by the reaction of ethylene dibromide
and potassium sulfide
, either alone3,4,5
or in phenol
and by the treatment of 2-mercaptoethanol
with a cation exchange resin.7
Chemical Abstracts Nomenclature (Collective Index Number);
sodium hydroxide (1310-73-2)
sodium bromide (7647-15-6)
ethylene dibromide (106-93-4)
potassium sulfide (1312-73-8)
phosphorus pentoxide (1314-56-3)
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