B.
N-Chlorocyclohexylideneimine. In a
500-ml. three-necked flask fitted with stirrer, addition funnel, thermometer, and
reflux condenser fitted with a calcium chloride tube are placed
15 g. (0.15 mole) of potassium acetate (Note
4) and
100 ml. of absolute ethanol. The mixture is heated to reflux temperature, and, when the
potassium acetate has dissolved, the
N,N-dichlorocyclohexylamine solution is added at such a rate as to maintain reflux (Note
5). The reaction mixture is heated under reflux for an additional 3 hours, during which time
potassium chloride precipitates. The mixture is cooled to room temperature,
200 ml. of ether and 100 ml. of water are added, and the resulting mixture is transferred to a
1-l. separatory funnel. The aqueous layer is separated and discarded. The ethereal layer is washed with three 100-ml. portions of water, three
50-ml. portions of 2N hydrochloric acid, and an additional three 100-ml. portions of water, the washings being discarded. The ethereal solution is dried over anhydrous
calcium sulfate, and the solvent is removed at room temperature with a
rotary evaporator and
water aspirator. The residue is transferred to a
25-ml. distilling flask and fractionally distilled at reduced pressure through a
short, vacuum-jacketed Vigreux column equipped with a Claisen type still head and a condenser through which ice water is circulated (Note
6).
N-Chlorocyclohexylideneimine, b.p.
53–54° (3 mm.) (
Caution! (Note 7)),
n25D 1.506, is obtained in
48–69% yield (
6.3–9.1 g.) (Note
8).