Org. Synth. 1957, 37, 50
DOI: 10.15227/orgsyn.037.0050
n-HEPTAMIDE
[Heptanamide]
Submitted by J. L. Guthrie and Norman Rabjohn
1.
Checked by William S. Johnson and Duane Zinkel.
1. Procedure
In a 1-l. round-bottomed flask, fitted with a thermometer extending nearly to the bottom, are placed 60 g. (1 mole) of urea and 69 g. (0.5 mole) of 95% n-heptanoic acid (Note 1). A condenser (Note 2) is attached to the flask, and the mixture is heated by means of an electric mantle. When the temperature reaches 140°, the urea is in solution, and a rather vigorous evolution of gas occurs which continues for several minutes. The temperature is maintained at 170–180° for 4 hours (Note 3), and then the mixture is allowed to cool.
As soon as the temperature drops to 110–120°, 400 ml. of 5% sodium carbonate solution is added carefully through the condenser, and the mixture is shaken vigorously (Note 4). The mixture is cooled in an ice bath, and the product is collected on a Büchner funnel. The solid, when dry, is slightly colored, and weighs 57–64 g., m.p. 85–91°.
The crude material is boiled for a few minutes with 200 ml. of 95% ethanol and a small amount of decolorizing carbon (Note 5). The mixture is filtered by gravity, and 800 ml. of water is added to the filtrate. The resulting slurry is cooled in an ice-salt bath and the solid is collected by filtration on a Büchner funnel. The product, which is almost colorless is air-dried. It weighs 44–48 g. (68–74%) and melts at 91–94° (Note 6). Evaporation of the filtrate under reduced pressure and reprecipitation of the residue from 20 ml. of 95% ethanol and 80 ml. of water affords an additional 3–4 g. (5–6%) of material which melts at 90–93°.
2. Notes
1.
Eastman Kodak Company, yellow label brand (95%), n-heptanoic acid was used.
2.
A condenser should be chosen which has an inside diameter of at least 1.5 cm.; otherwise frequent loosening of the sublimate is required to prevent clogging. A 3-ft., air-cooled tube with an internal diameter of about 2.5 cm. serves as a satisfactory condenser.
3.
Temperatures below 170° lead to slightly lower yields, and temperatures above 180° cause excessive sublimation of
urea. Although the reaction is nearly complete after 2 hours, the yield appears to be improved by additional heating.
4.
Failure to make the mixture basic leads to the formation of a greasy, colored product.
5.
A small amount of solid does not dissolve in the alcohol.
6.
Recrystallization from dilute
ethanol affords colorless material, m.p.
94–95°.
3. Discussion
Heptamide has been prepared by heating
heptanoic acid with
ammonia in a
sealed tube2 at 230°, by treating
heptanoic anhydride with
ammonia,
3 by passing
ammonia through
heptanoic acid4 at 125–190°, by the rearrangement of
heptaldehyde oxime in the presence of
Raney nickel in a quartz tube at 150° for 5 minutes,
5 by the Willgerodt reaction with
2-, 3-, or 4-heptanone or
heptanal,
6,7 and by the action of
ammonia on
heptanoyl chloride.
8
The procedure described is based on the method of E. Cherbuliez and F. Landolt,
9 by which formic and acetic acids were converted into the corresponding amides.
Appendix
Chemical Abstracts Nomenclature (Collective Index Number);
(Registry Number)
Heptamide
heptaldehyde oxime
2-, 3-, or 4-heptanone
ethanol (64-17-5)
ammonia (7664-41-7)
sodium carbonate (497-19-8)
Raney nickel (7440-02-0)
decolorizing carbon (7782-42-5)
urea (57-13-6)
Heptanoic acid,
n-HEPTANOIC ACID (111-14-8)
Heptanal (111-71-7)
heptanoic anhydride (626-27-7)
heptanoyl chloride (2528-61-2)
Heptanamide (628-62-6)
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