Org. Synth. 1947, 27, 56
DOI: 10.15227/orgsyn.027.0056
N-METHYL-1-NAPHTHYLCYANAMIDE
[Cyanamide, methyl-(1-naphthyl)-]
Submitted by Homer W. J. Cressman
Checked by Nathan L. Drake and Werner R. Boehme..
1. Procedure
Caution! Cyanogen bromide is highly toxic. This preparation should be carried out under a good hood.
A mixture of
171 g. (1 mole) of dimethyl-α-naphthylamine (Note 1) and
125 g. (1.2 moles) of cyanogen bromide1 in a
1-l. flask (Note 2) is heated under reflux on the
steam bath for 16 hours
(Note 3). The cooled reaction mixture is added to
2.5 l. of dry ether, and the insoluble quaternary salt
(Note 4) is filtered. The
ether filtrate is extracted with four
800-ml. portions of approximately 15% hydrochloric acid solution
(Note 5) and washed with five 500-ml. portions of water. The
ether solution is dried with
30–35 g. of anhydrous calcium sulfate (Drierite). After filtration, the solvent is removed by distillation at atmospheric pressure on the steam bath; the residue is fractionated under reduced pressure. The yield of pale yellow oil, boiling at
170–171°/1 mm. (
185–187°/3 mm.), amounts to
115–122 g. (
63–67%)
(Note 6).
2. Notes
1.
Better yields are obtained by dealkylating the tertiary amine in this manner than by starting with the secondary amine. In a similar manner,
N-ethyl-1-naphthylcyanamide, b.p.
165–168°/2 mm., is obtained in a
48% yield from
diethyl-α-naphthylamine; the yield from the secondary amine is only
25%.
2.
Ground-glass equipment is preferable.
3.
In order to avoid loss of
cyanogen bromide an efficient condenser must be used and the heating should be very gradual at first.
4.
About
10 g. of α-naphthyltrimethylammonium bromide, m.p.
160°, is generally obtained.
5.
About
25 g. of crystalline dimethyl-α-naphthylamine hydrochloride may be recovered by efficient chilling of the
hydrochloric acid extracts.
6.
The
N-methyl-1-naphthylcyanamide turns dark green upon standing exposed to the air for several days. It may be preserved in sealed, evacuated ampoules in the absence of light.
3. Discussion
The preparation described is based on the method of von Braun and co-workers.
2This preparation is referenced from:
Appendix
Chemical Abstracts Nomenclature (Collective Index Number);
(Registry Number)
dimethyl-α-naphthylamine
diethyl-α-naphthylamine
dimethyl-α-naphthylamine hydrochloride
hydrochloric acid (7647-01-0)
ether (60-29-7)
calcium sulfate (7778-18-9)
Cyanogen bromide (506-68-3)
N-Methyl-1-naphthylcyanamide,
Cyanamide, methyl-(1-naphthyl)- (53663-33-5)
N-ethyl-1-naphthylcyanamide
α-naphthyltrimethylammonium bromide
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