A Publication
of Reliable Methods
for the Preparation
of Organic Compounds
Annual Volume
Org. Synth. 1947, 27, 58
DOI: 10.15227/orgsyn.027.0058
[Urea, 1-methyl-1-(1-naphthyl)-2-thio-]
Submitted by Homer W. J. Cressman
Checked by Nathan L. Drake and Werner R. Boehme.
1. Procedure
The apparatus, consisting of a 1-l. three-necked flask, fitted with a glycerol-sealed mechanical stirrer, two inlet tubes (10-mm. bore) extending nearly to the blades of the stirrer, and an outlet tube (Note 1), is set up in a good hood. Into a solution of 91 g. (0.5 mole) of N-methyl-1-naphthylcyanamide (p. 608) in 350 ml. of absolute ethanol, mechanically stirred and cooled by immersion of the flask in a water bath maintained at 20–25°, ammonia is bubbled at a moderate rate. After 5 minutes, hydrogen sulfide (Note 2) is passed into the solution at about the same rate. The introduction of ammonia is continued for 1.5 hours; hydrogen sulfide is passed into the mixture an additional 30 minutes. A white solid begins to separate soon after the first addition of hydrogen sulfide. After the mixture is chilled in an ice-salt bath, it is filtered. The solid is suspended in 350 ml. of cold water, again separated by filtration, and finally washed with two 100-ml. portions of water, then with two 100-ml. portions of methanol, and dried. The yield of 1-methyl-1-(1-naphthyl)-2-thiourea, m.p. 168–170° (Note 3), amounts to 89–97 g. (82–90%); this material is suitable for most purposes.
2. Notes
1. The use of an alkali trap1 is recommended.
2. This general reaction can be used for preparing other unsymmetrical thioureas when the desired cyanamides can be obtained. The submitter has also prepared 1-methyl-1-(1-naphthyl)-2-selenourea, m.p. 174–175° with decomposition, and 1-ethyl-1-(1-naphthyl)-2-selenourea, m.p. 168–170° with decomposition, by substitution of hydrogen selenide for hydrogen sulfide.
3. The thiourea can be further purified by recrystallization from ethanol. The recrystallized product melts at 170–171°.
3. Discussion
The preparation of this compound is not reported in the literature.
This preparation is referenced from:

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

ethanol (64-17-5)

ammonia (7664-41-7)

methanol (67-56-1)

hydrogen sulfide (7783-06-4)

thiourea (62-56-6)

Urea, 1-methyl-1-(1-naphthyl)-2-thio- (53663-34-6)

N-Methyl-1-naphthylcyanamide (53663-33-5)



hydrogen selenide (7782-49-2)