In a
2-l. round-bottomed flask, fitted with a reflux condenser and a 6-mm. glass tube closed at the upper end with a rubber tube and pinch-cock and reaching to the bottom of the flask, are placed
800 cc. of absolute alcohol and
50.6 g. (2.2 gram atoms) of clean sodium cut in small pieces. When the
sodium is completely dissolved, one half of the solution is transferred to a
2-l. three-necked, round-bottomed flask fitted with a dropping funnel, a
liquid-sealed mechanical stirrer, and a
reflux condenser closed by a calcium chloride tube. The flask containing the remainder of the solution is connected again to the reflux condenser, and
hydrogen sulfide from a
cylinder is introduced by means of the
glass tube at the rate of about two bubbles per second until the solution is saturated (about six hours is required). This solution of
sodium hydrogen sulfide is added to the
sodium ethoxide solution in the three-necked flask, and the mixture is refluxed for one hour. After cooling to room temperature, sufficient absolute
alcohol (about 200 cc.) is added to dissolve all the
sodium sulfide (Note
1).
To this solution of
sodium sulfide is added dropwise with stirring
246 g. (2 moles) of n-propyl bromide (
Org. Syn. Coll. Vol. I, 1941, 37 and
p. 359 above). After all the
bromide has been added the flask is heated on a steam cone for eight hours (Note
2), during which time the mixture should not be stirred too vigorously. It is then cooled and added to
2 l. of 25 per cent aqueous sodium chloride solution contained in a
separatory funnel. The mixture is shaken to ensure thorough mixing, allowed to stand until the layers have separated, and the upper oily layer of
propyl sulfide removed and dried with anhydrous
sodium sulfate. The lower layer is extracted with five
200-cc. portions of petroleum ether (b.p.
25–45°) (Note
3), the extract dried with 20 g. of
sodium sulfate, and the
petroleum ether distilled through a
60-cm. fractionating column until the temperature of the vapors passing over reaches 60°. The residue is added to the crude
propyl sulfide previously separated and the combined portions distilled. The yield of product boiling at
140–143° is
80–100 g. (
68–85 per cent of the theoretical amount) (Note
4).