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. (
54–62%). In addition,
28–38 g. of unchanged cyclohexanone boiling at
51–52°/17 mm.,
15–35 g. of
diallylcyclohexanone boiling at
123–124°/17 mm., and small intermediate fractions are obtained.