Organic Syntheses, Coll. Vol. 3, p.44 (1955); Vol. 28, p.8 (1948).
Approximately 1.5 l. of anhydrous liquid ammonia
is introduced into a dry 5-l. three-necked flask
fitted with a sealed mechanical stirrer
and an efficient reflux condenser
which is connected through a sodalime tube
to a gas-absorption trap
. Freshly cut sodium (47.2 g., 2.05 gram atoms)
is converted to sodium amide
by addition to the liquid ammonia
in the presence of a small amount of ferric nitrate
, according to p. 219
. A 1-l. dropping funnel
and a gas inlet tube
connected to a source of dry nitrogen
are attached to the third neck of the flask, and, after the blue color of the solution has disappeared and a gray suspension of sodium amide
remains (Note 1)
, 1.2 l. of dry ether
is added as rapidly as the rate of vaporization of ammonia
will permit. The ammonia
is removed by warming the flask on a steam bath
until refluxing of the ether
occurs. Cyclohexanone (Note 2) (220 g., 2.24 moles)
is added through the dropping funnel (Note 3)
, and the mixture is stirred and heated under reflux on a steam bath for 3 hours. Nitrogen
is then introduced through the gas inlet tube to maintain an inert atmosphere (Note 4)
, and the mixture is cooled in an ice bath
. A solution of 246 g. (2.03 moles) of allyl bromide (Note 5)
in 1 l. of anhydrous ether
is added rapidly through the dropping funnel with stirring. If the reaction does not start soon after the completion of this addition the mixture is warmed cautiously on the steam bath. When the exothermic reaction has started it is controlled by cooling in the ice bath while refluxing continues for 20–30 minutes. The mixture is finally heated under reflux on the steam bath for 3 hours.
The mixture is cooled in an ice bath, any sodium
or sodium amide
which may remain in the necks of the flask is scraped into the reaction mixture with a spatula
, and enough water is added to dissolve the sodium bromide
. The ether
layer is separated and combined with five 100-ml. ether
extracts of the aqueous phase, washed with 150 ml. of saturated sodium chloride
solution, and dried over anhydrous sodium sulfate
. The ether
is removed by distillation, and the residue is fractionated carefully under reduced pressure through a 4-ft. heated column
packed with glass helices and fitted with a total-condensation variable take-off head. The yield of 2-allylcyclohexanone
boiling at 90–92°/17 mm
. is 153–174 g.
). In addition, 28–38 g. of unchanged cyclohexanone
boiling at 51–52°/17 mm.
, 15–35 g.
boiling at 123–124°/17 mm.
, and small intermediate fractions are obtained.
The conversion of the sodium
to sodium amide
requires 30–90 minutes. More liquid ammonia
may be added if too much is lost by vaporization before the conversion is complete.
The submitters obtained equally good results by adding 80 g. (2.05 moles) of freshly prepared finely powdered sodium amide
in portions to a solution of the cyclohexanone
in 1.2 l. of dry ether
, heating under reflux for 3 hours, and continuing the preparation in the manner described.
The submitters state that the yield is increased appreciably if a nitrogen
atmosphere is maintained after this point. Loss of ether
may be avoided by stopping the flow of nitrogen
when refluxing begins.
This preparation is referenced from:
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