In a
600-ml. beaker equipped with a
stirrer,
thermometer, and
dropping funnel are placed
24.6 g. (0.1 mole) of finely powdered 1,2-di-1-(1-cyano)cyclohexylhydrazine (p.
274) and
130 ml. of 90% ethanol. To this mixture is added slowly, with cooling,
45 ml. of concentrated hydrochloric acid. The beaker is placed in an
ice bath, and, after the suspension has been cooled to 10°,
bromine is added at such a rate that the temperature does not rise above 15°. About
16–17 g. (about 0.1 mole) of bromine is required to reach the end point characterized by Permanent orange-yellow color. The reaction mixture is poured into 80 ml. of ice water. After 15 minutes the suspension is filtered with the aid of a
Büchner funnel, washed with 250 ml. of water, and pressed dry. The solid is transferred to a
500-ml. Erlenmeyer flask,
120 ml. of boiling 95% ethanol is added, and the crude product is dissolved as rapidly as possible while being heated on a
steam bath (Note
1). The solution is filtered through a fluted filter in a
heated funnel, and the filtrate is placed in a
refrigerator overnight. The solid is collected on a Büchner funnel and dried in a
vacuum desiccator over
calcium chloride. The yield of product is
20.5–22.0 g. (
84–90%); m.p.
113.5–115.5° (Note
2) and (Note
3).