A solution of
196 g. (1 mole) of cyclohexanone diallyl acetal (Note
1),
150 g. of toluene, and
0.10 g. of p-toluenesulfonic acid is distilled through a good
fractionating column (Note
2). In about 3 hours, 110 g. of distillate boiling at 91–92° (Note
3) is obtained and the temperature in the head then rises abruptly. The residue in the distilling flask is cooled and washed with
5 ml. of aqueous potassium carbonate to remove the acid. The remaining solution is passed through a filter containing anhydrous powdered
magnesium sulfate and returned to the still. Most of the remaining
toluene is removed by distillation at 100 mm. pressure (b.p.
52°). The
receiver is changed, the pressure is reduced to 15 mm., and the last of the
toluene is collected in a cold
trap. The residual oil is rapidly vacuum-distilled to separate the product from a higher-boiling residue. Redistillation yields
117–126 g. (
85–91%) of
2-allylcyclohexanone, b.p.
86–88°/15 mm.,
nD25 1.4670.