Org. Synth. 1956, 36, 48
DOI: 10.15227/orgsyn.036.0048
LAURYLMETHYLAMINE
[Dodecylamine, N-methyl-]
Submitted by C. V. Wilson and J. F. Stenberg
1.
Checked by N. J. Leonard and C. W. Schimelpfenig.
1. Procedure
In a 5-l. three-necked flask, fitted with a ball-joint sealed stirrer and a Soxhlet extractor (70 mm. internal diameter × 300 mm. length of body) carrying a large-capacity condenser, are placed 1.8 l. of dry ether (Note 1) and 38 g. (1 mole) of finely divided lithium aluminum hydride (Note 2). In the Soxhlet cup is placed 160 g. (0.75 mole) (Note 3) of N-methyllauramide (m.p. 67–69°) (Note 4). The mixture is heated under gentle reflux with efficient stirring over a 5-hour period and then stirred overnight at room temperature (Note 5); the N-methyllauramide is extracted from the cup during the first 3 hours.
The excess lithium aluminum hydride and the metallic complexes are decomposed by the careful addition of 82 ml. of distilled water, from a dropping funnel, to the well-stirred mixture. The reaction mixture is stirred for an additional 30 minutes, filtered with suction, and the solid is washed with several 100-ml. portions of ether. After the ether is removed from the filtrates, the residual oil is distilled under reduced pressure. The yield of laurylmethylamine, a colorless liquid boiling at 110–115°/1.2–1.5 mm., is 121–142 g. (81–95%) (Note 6).
2. Notes
1.
It is preferable to use
ether subjected to final drying by distillation from
lithium aluminum hydride.
2.
The yield depends upon the use of high-quality, fresh
lithium aluminum hydride.
3.
If a Soxhlet extractor having a smaller capacity is employed, the cup will have to be recharged during the course of the reaction.
4.
N-Methyllauramide,
N-methylmyristamide, and
N-methylpelargonamide can be prepared in 95–98% yield by adaptation of the method used by Roe, Scanlan, and Swern
2 for the preparation of amides of oleic and 9,10-dihydroxystearic acids.
5.
Stirring overnight is a matter of convenience. In the preparation of
methylnonylamine, refluxing for an hour after the addition of the amide was found by the submitters to be sufficient.
6.
Methylnonylamine and
methylmyristylamine were prepared by the submitters in 89–92% yield using the same procedure; with
methylmyristylamine a longer reflux period was required, owing to the lower solubility of the amide.
3. Discussion
Laurylmethylamine has been prepared by the reaction of
lauryl alcohol with
methylamine under pressure in the presence of catalysts at high temperature,
3 by heating
lauryl chloride with
methylamine in alcoholic or aqueous medium under pressure,
4,5,6 by the reaction of lauryl halides with aqueous
methylamine,
7 by the hydrolysis of
o-carboxy-N-methyl-N-laurylbenzenesulfonamide,
8 and by the pyrolysis of
β-cyanoethyllaurylmethylamine.
9 Cetylmethylamine has been prepared by the catalytic debenzylation of
benzylcetylmethylamine.
10
Appendix
Chemical Abstracts Nomenclature (Collective Index Number);
(Registry Number)
ether (60-29-7)
Lauryl alcohol (112-53-8)
methylamine (74-89-5)
lithium aluminum hydride (16853-85-3)
Laurylmethylamine,
Dodecylamine, N-methyl- (7311-30-0)
N-methyllauramide (27563-67-3)
N-methylpelargonamide
methylnonylamine (39093-27-1)
methylmyristylamine
lauryl chloride (112-52-7)
β-cyanoethyllaurylmethylamine
Cetylmethylamine
benzylcetylmethylamine
o-carboxy-N-methyl-N-laurylbenzenesulfonamide
N-methylmyristamide (7438-09-7)
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