Organic Syntheses, Coll. Vol. 3, p.370 (1955); Vol. 23, p.32 (1943).
In a 2-l. three-necked flask
, fitted with a mechanical stirrer (Note 1)
, a reflux condenser
, and a dropping funnel
, is placed 630 g. (670 ml., 7 moles) of β-ethoxyethyl alcohol (Note 2)
. The stirrer is started, and 600 g. (210 ml., 2.2 moles) (Note 3) of phosphorus tribromide
is added from the dropping funnel over a period of 1.5–2 hours. The temperature is permitted to rise until the reaction mixture refluxes gently.
The mixture is then distilled, and the distillate boiling below 150° is collected in a 2-l. flask containing 1 l. of water. The lower layer of crude β-ethoxyethyl bromide
is separated and dried over 10 g. of calcium chloride
. The liquid is decanted and distilled through a 25-cm. fractionating column
, and the fraction boiling at 125–127°/760 mm
. is collected (Note 4)
. The yield of pure product is 660–670 g.
based on the phosphorus tribromide
A rubber sleeve lubricated with a drop of oil provides an effective seal for the stirrer.
The first fraction, boiling at 38–40°
, is ethyl bromide, and it weighs 120–130 g.
Lower yields (56–59%
) of β-ethoxyethyl bromide
are obtained by distillation without a fractionating column. The residue, however, should not be overheated, for at high temperatures phosphorous acid
decomposes to give phosphine
and perhaps even elementary phosphorus
, and then, when air is admitted to the apparatus an explosion may occur. A minor explosion in connection with this preparation has been reported (N. L. Drake, private communication) and a similar situation has been observed in reactions with phosphorus trichloride
This preparation is referenced from:
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