Organic Syntheses, Coll. Vol. 4, p.955 (1963); Vol. 31, p.111 (1951).
A solution of 138 g. (175 ml., 3 moles) of absolute ethanol (Note 1)
and 447 g. (477 ml., 3 moles) of freshly distilled diethylaniline
in 1 l. of dry petroleum ether
) is placed in a 3-l. three-necked flask
fitted with a sealed stirrer, an efficient reflux condenser
, and a 500-ml. dropping funnel (Note 2)
which is charged with a solution of 137.5 g. (87.5 ml., 1 mole) of freshly distilled phosphorus trichloride
in 400 ml. of dry petroleum ether
). The flask is cooled in a cold-water bath
. With vigorous stirring (Note 3)
, the phosphorus trichloride
solution is introduced at such a rate that the mixture boils gently towards the end of the addition. After the addition, which requires about 30 minutes, the mixture is heated under gentle reflux for about 1 hour with stirring. The suspension, containing a copious precipitate of diethylaniline hydrochloride
, is then cooled and filtered with suction through a sintered-glass funnel
. The cake of the amine salt is well compressed and washed with five 100-ml. portions of dry petroleum ether
). The filtrate and washings are combined and concentrated by distillation at water-bath temperature through a 75-cm. Vigreux column
. The residue is transferred to a pear-shaped flask
and distilled under water-pump vacuum through a 75-cm. Vigreux column. After a small fore-run, the product is collected at 57–58°/16 mm.
, 43–44°/10 mm.
). The yield of colorless product is 138 g.
0.963 (Note 4)
and (Note 5)
It is convenient to connect the dropping funnel to the flask by a piece of 20-mm. glass tubing about 10 cm. long which is sleeved into the neck of the flask by a section of rubber tubing. By this means, the rate of introduction of the phosphorus trichloride
solution may be readily observed and clogging by the copious precipitate of diethylaniline hydrochloride
The recovered petroleum ether
and fore-run contain some of the product. By using the recovered petroleum ether
in subsequent runs and adding the fore-run before the final distillation, the yield is increased to 86–90%.
This preparation is referenced from:
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