Org. Synth. 1931, 11, 58
DOI: 10.15227/orgsyn.011.0058
n-HEPTYLAMINE
Submitted by W. H. Lycan, S. V. Puntambeker, and C. S. Marvel.
Checked by W. H. Carothers and W. L. McEwen.
1. Procedure
A solution of
258 g. (2 moles) of heptaldoxime (p. 313) in 4 l.
of absolute alcohol (Note 1) is heated to boiling in a
12-l. round-bottomed flask on a
steam bath. The flask is equipped with a
150-cm. reflux condenser in which the inner tube is very wide (2.5 cm.). As soon as the alcohol begins to boil, the steam is shut off and the temperature is maintained by introducing strips of
sodium through the top of the condenser. The total amount of
sodium added is 500 g., and it should be added as rapidly as is possible without loss of alcohol
(Note 2). The last
150 g. of sodium melts in the hot mixture and may be added very rapidly without loss of alcohol or amine.
As soon as the sodium has dissolved, the contents of the flask are cooled and diluted with 5 l. of water. The flask is equipped at once with a condenser set for distillation, and the distillate is carried below the surface of a solution of 300 cc. of concentrated hydrochloric acid in 300 cc. of water in a 12-l. flask. The distillation is continued as long as any basic material passes over. When frothing interferes toward the end of the distillation an additional 3 l. of water is added to the distillation flask. The total distillate is 8–9 l.
The alcohol, water, and unreacted oxime are removed by heating the acid distillate on the steam cone under reduced pressure (about 20–30 mm.); the amine hydrochloride crystallizes in the flask. The flask is then cooled and equipped with a reflux condenser through which 1 l. of 40 per cent potassium hydroxide solution is introduced. The hydrochloride is washed down from the sides of the flask, and the resulting mixture is cooled and transferred to a separatory funnel. The lower alkaline layer is removed and solid potassium hydroxide is added to the amine in the funnel. The aqueous layer is removed and fresh sticks of potassium hydroxide are added from time to time until no further separation of an aqueous alkaline solution occurs. Twenty-four to thirty hours is required for complete drying. The amine is then decanted through the top of the funnel into a 250-cc. modified Claisen flask and distilled. The n-heptylamine is collected at 152–157°. The yield is 140–170 g. (60–73 per cent of the theoretical amount) (Note 3).
2. Notes
1.
The yields are poor if the alcohol is not completely dehydrated. A very satisfactory grade of alcohol is obtained by distilling ordinary absolute alcohol from
magnesium methoxide (Org. Syn. Coll. Vol. I, 1941, 249).
2.
The best yields are obtained when the reduction is carried out rapidly.
3.
Using essentially the same method the following amines have been prepared in 50–60 per cent yields:
n-butylamine, b. p.
75–80°, from
butyraldoxime;
sec.-butylamine, b. p.
59–65°, from
ethyl methyl ketoxime;
cyclohexylamine, b. p.
133–135°, from
cyclohexanone oxime. Greater care must be observed in drying the butylamines.
3. Discussion
n-Heptylamine can be prepared by the reduction of
heptaldoxime with
sodium amalgam and acetic acid,
1 with
ammonium amalgam,
2 with
sodium and an alcohol,
3 and catalytically;
4 by the reduction of
1-nitroheptane with
iron and acetic acid;
5 by the reduction of
heptanonitrile with
sodium and an alcohol
3,
6 or catalytically;
7 by the reduction of
heptanoamide with
sodium and an alcohol
8 or catalytically;
9 by the reduction of
heptaldehyde phenylhydrazone with
sodium amalgam and
acetic acid;
10 and by the catalytic reduction of
heptaldehyde and
ammonia in alcohol.
11 12 The formation of a secondary amine, which is a serious limitation in the catalytic reduction of
heptanonitrile, can be almost completely suppressed by reducing in the presence of a large amount of
ammonia.
12
Other methods which also lead to
n-heptylamine are the reaction between
1-bromoheptane and
ammonia;
13 the Hofmann rearrangement of the
amide of caprylic acid;
14 and the Beckmann rearrangement of
methyl n-heptyl ketoxime, followed by hydrolysis.
15This preparation is referenced from:
Appendix
Chemical Abstracts Nomenclature (Collective Index Number);
(Registry Number)
Heptaldoxime
heptaldehyde phenylhydrazone
amide of caprylic acid
alcohol (64-17-5)
hydrochloric acid (7647-01-0)
acetic acid (64-19-7)
ammonia (7664-41-7)
iron (7439-89-6)
potassium hydroxide (1310-58-3)
sodium (13966-32-0)
magnesium methoxide
n-butylamine (109-73-9)
Cyclohexanone oxime (100-64-1)
Ammonium (14798-03-9)
heptanonitrile (629-08-3)
butyraldoxime
ethyl methyl ketoxime
cyclohexylamine (108-91-8)
1-nitroheptane
heptanoamide
1-bromoheptane (629-04-9)
heptaldehyde (111-71-7)
n-heptylamine (111-68-2)
sec.-butylamine (13952-84-6)
methyl n-heptyl ketoxime
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