A Publication
of Reliable Methods
for the Preparation
of Organic Compounds
Annual Volume
Org. Synth. 1935, 15, 72
DOI: 10.15227/orgsyn.015.0072
Submitted by R. W. Bost and M. W. Conn.
Checked by Reynold C. Fuson and Charles F. Woodward.
1. Procedure
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).
2. Notes
1. It is best to have the sodium sulfide completely dissolved before it is added to the bromide; subsequent extraction is facilitated, however, if the solution is kept at a minimum volume.
2. In order to be certain that no propyl sulfide is being lost during the refluxing, the condenser should be connected to a trap containing an aqueous solution of mercuric chloride. Condenser water cooled to 5–10° is recommended.
3. To avoid contamination of the product the petroleum ether should be distilled before being used. Ethyl ether is not suitable for this extraction.
4. n-Butyl and sec.-amyl sulfides can be prepared by procedures essentially the same as that given here.
3. Discussion
n-Propyl sulfide has always been prepared by the action of an alcoholic solution of an alkali sulfide on a n-propyl halide.1

References and Notes
  1. Cahours, Compt. rend. 76, 133 (1973); Winssinger, Bull. soc. chim. (2) 48, 109 (1887).

Chemical Abstracts Nomenclature (Collective Index Number);
(Registry Number)

petroleum ether

alcohol (64-17-5)

ethyl ether (60-29-7)

sodium chloride (7647-14-5)

hydrogen sulfide (7783-06-4)

bromide (24959-67-9)

n-PROPYL BROMIDE (106-94-5)

sodium sulfate (7757-82-6)

sodium (13966-32-0)

sodium ethoxide (141-52-6)

mercuric chloride (7487-94-7)

sodium sulfide (1313-82-2)

sodium hydrogen sulfide

Propyl sulfide,
n-PROPYL SULFIDE (111-47-7)

n-butyl sulfide (544-40-1)

n-amyl sulfide