A Publication
of Reliable Methods
for the Preparation
of Organic Compounds
Annual Volume
Org. Synth. 1934, 14, 54
DOI: 10.15227/orgsyn.014.0054
[Ethanol, 2-methylmercapto-]
Submitted by Wallace Windus and P. R. Shildneck.
Checked by H. T. Clarke and S. Gurin.
1. Procedure
A 2-l. three-necked flask is fitted with a dropping funnel, a stopcock, and a long condenser. The end of the condenser is connected with the following assembly: a safety trap, consisting of an empty gas-washing bottle; a second wash bottle containing 100 cc. of dilute sulfuric acid (1 volume of concentrated sulfuric acid to 2 volumes of water); a tower, about 30 cm. high, containing calcium chloride; an empty 2-l. flask which acts as a trap; a 2-l. flask containing 80.5 g. (3.5 gram atoms) of clean sodium dissolved in 1.5 l. of absolute alcohol; an empty 1-l. flask and a 1-l. flask containing 500 cc. of a saturated solution of lead acetate (Note 1). The exit tube from this last flask leads to a suction pump.
After 556 g. (2 moles) of methyl isothiourea sulfate (p. 411) is placed in the three-necked flask, a very slow current of air is drawn through the apparatus by means of the suction pump while 800 cc. of cold 5 N sodium hydroxide is added to the methyl isothiourea sulfate through the dropping funnel. The mixture is warmed very slowly to generate the methyl mercaptan (Note 2). As the reaction nears completion (after about two hours), the mixture is heated strongly for about thirty minutes (Note 3).
The solution of sodium methyl sulfide in absolute alcohol is transferred to a 3-l. three-necked flask, which is placed on a steam bath and fitted with a dropping funnel, a reflux condenser, and a mechanical stirrer. The solution is heated until the alcohol begins to boil. Heating is then discontinued and 302 g. (3.75 moles) of ethylene chlorohydrin (Note 4) is added dropwise with efficient stirring over a period of about two hours (Note 5). The reaction mixture is concentrated by distilling as much of the alcohol as possible on the steam bath. The mixture is then allowed to cool and the sodium chloride removed by filtration. The flask is rinsed and the sodium chloride washed with three 100-cc. portions of 95 per cent alcohol. The combined filtrate and washings are concentrated on the steam bath under reduced pressure until no further distillate passes over. The residue is then transferred to a modified Claisen flask and fractionally distilled under reduced pressure. The yield is 238–265 g. (74–82 per cent of the theoretical amount based on the sodium used) of a product boiling at 68–70°/20 mm. (Note 6).
2. Notes
1. The lead acetate removes any unreacted methyl mercaptan by precipitating it as the lead salt.
2. The rate of heating controls the rate of evolution of the methyl mercaptan. After the rapid evolution of the gas begins, the reaction mixture should be heated very gently. The slight suction aids in obtaining a regular flow of the gas.
3. The evolution of methyl mercaptan is almost complete after one and one-half to two hours. Prolonged vigorous heating increases the amount of ammonia evolved.
4. The ethylene chlorohydrin should be redistilled and the fraction boiling at 126–128° should be used.
5. The reaction is usually complete immediately after the addition of the ethylene chlorohydrin, obviating the necessity for refluxing the mixture. When the reaction is complete the solution is neutral to litmus paper.
6. Quantities of material five times as large as those called for above may be used without decreasing the percentage yield of product. With the larger amounts of material it is more convenient to filter the sodium chloride before concentrating the solution.
3. Discussion
The methods for preparing methyl mercaptan and β-hydroxyethyl methyl sulfide are essentially those of Arndt1 and Kirner,2 respectively.
This preparation is referenced from:

References and Notes
  1. Arndt, Ber. 54, 2238 (1921).
  2. Kirner, J. Am. Chem. Soc. 50, 2451 (1928).

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

alcohol (64-17-5)

ammonia (7664-41-7)

sodium hydroxide (1310-73-2)

sodium chloride (7647-14-5)

sodium (13966-32-0)

lead acetate

ethylene chlorohydrin (107-07-3)

β-Hydroxyethyl methyl sulfide,
Ethanol, 2-methylmercapto- (5271-38-5)

methyl isothiourea sulfate

methyl mercaptan (74-93-1)

methyl sulfide (75-18-3)