In a
2-l. round-bottomed flask are placed
120 g. (1.83 moles) of 92% ethylenediamine (Note
1),
300 ml. of 95% ethanol, and 300 ml. of water. The flask is attached to an
efficient reflux condenser, and
121 ml. of carbon disulfide is placed in a
separatory funnel attached to the top of the condenser by means of a
notched cork. About
15 to 20 ml. of the carbon disulfide is added, and the flask is shaken to mix the contents. A vigorous reaction takes place (Note
2), and it may be necessary to cool the flask. After the reaction has started, a
water bath at 60° is placed under the flask and the balance of the
carbon disulfide is added at such a rate that the vapors reflux about one-third the way up the condenser. About 2 hours is required for the addition of the
carbon disulfide. At this time the bath temperature is raised to about 100°, and the mixture is allowed to reflux for 1 hour. Then
15 ml. of concentrated hydrochloric acid is added, and the mixture is refluxed under a good
hood (bath at 100°) for 9–10 hours. The mixture is cooled in an
ice bath, and the product is filtered by suction on a
Büchner funnel and washed with
200–300 ml. of cold acetone (Note
3). A yield of
156–167 g. (
83–89%) of white crystals is obtained melting at
197–198° (Note
4) and (Note
5).