Organic Syntheses, Coll. Vol. 1, p.192 (1941); Vol. 5, p.37 (1925).
In a 1-l. distilling flask (Note 1)
, fitted with a thermometer
reaching within 5 mm. of the bottom, is placed an intimate mixture of 200 g. (1.34 moles) of powdered adipic acid (Note 2)
and 10 g. of finely ground crystallized barium hydroxide
. The mixture is gradually heated in a fusible alloy bath (Note 3)
to 285–295° (Note 4)
during about one and one-half hours, and maintained at that temperature until only a small amount of dry residue remains in the flask. This requires about two hours longer. The cyclopentanone
distils slowly, accompanied by small quantities of adipic acid
The ketone is separated from the water in the distillate, either by salting out with calcium chloride
or by extracting with a little ether (Note 5)
. It is washed with a little aqueous alkali and then with water, dried over calcium chloride
, and distilled through a good fractionating column (Note 6)
. The fraction boiling at 128–131°
. The yield is 86–92 g.
per cent of the theoretical amount).
If larger runs are made, a three-necked flask
provided with a mechanical stirrer
should be used for the reaction.
The unrecrystallized adipic acid
, prepared as described on p. 18
, may be used.
An air bath
may be used, but the metal bath
insures better temperature control.
If the temperature goes above 300°, the adipic acid
begins to distil quite rapidly. It is best to hold the temperature as near 290° as is possible.
is quite volatile with ether
vapor, and careful fractionation is necessary when ether
is used for the separation of the ketone from the water.
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