In a
500-ml. round-bottomed flask attached to a
modified Dean and Stark constant water separator1 (Note
1) which is connected to a
reflux condenser are placed
67.8 g. (0.60 mole) of ethyl cyanoacetate (Note
2),
56.8 g. (0.66 mole) of diethyl ketone (Note
3),
9.2 g. (0.12 mole) of ammonium acetate,
30 g. (0.48 mole) of glacial acetic acid, and
100 ml. of benzene. The flask is heated in an
oil bath at 160–165°, and the water that distils out of the mixture with the refluxing
benzene is removed from the separator at intervals. Refluxing is continued for 24 hours (several hours after the separation of water has ceased) (Note
4).
The solution is cooled and washed with three
25-ml. portions of 10% sodium chloride solution, after which the
benzene is removed by distillation under reduced pressure. The residue is transferred to a
1-l. bottle, a solution of
78 g. (0.75 mole) of commercial sodium bisulfite in 310 ml. of water is added, and the mixture is shaken on a mechanical shaker for 2 hours. The turbid solution is diluted with 500 ml. of water and extracted with three
50-ml. portions of benzene. The extracts are discarded (Note
5). The bisulfite solution is then cooled in an
ice bath, and an ice-cold solution of
32 g. (0.8 mole) of sodium hydroxide in 130 ml. of water is added dropwise with mechanical stirring. The ester which separates is extracted at once with four
25-ml. portions of benzene (Note
6). The
benzene solution is washed with
50 ml. of 1% hydrochloric acid, dried for a short time over
20 g. of anhydrous sodium sulfate, filtered into a
250-ml. modified Claisen flask, and distilled under reduced pressure. The yield of ester boiling at
123–125°/12 mm. (Note
7) is
65.4–75 g. (
60.5–68%) (Note
8), (Note
9), and (Note
10).