Org. Synth. 1925, 4, 47
DOI: 10.15227/orgsyn.004.0047
METHYLENEAMINOACETONITRILE
[α-Hydroformamine cyanide]
Submitted by Roger Adams and W. D. Langley.
Checked by H. T. Clarke and E. R. Taylor.
1. Procedure
In a 5-l. round-bottomed flask, fitted with a mechanical stirrer and surrounded by an ice-salt bath, are placed 1620 g. (1.5 l., 18.9 moles) of technical formaldehyde (sp. gr. 1.078/20°) (Note 1) and 540 g. (10 moles) of ammonium chloride. A thermometer is placed in the liquid, which is cooled to 0°. This temperature is maintained throughout the entire reaction (Note 2). Stirring is commenced (Note 3), and a solution of 490 g. (9.8 moles) of 98 per cent sodium cyanide in 850 cc. of water is dropped into the mixture of ammonium chloride and formaldehyde at such a rate (about 90 drops per minute) that at least six hours will be required for this addition.
When one-half the sodium cyanide solution has been added, all the ammonium chloride will be in solution. At this point, the addition of 380 cc. of glacial acetic acid is started at such a rate (2–2.5 cc. per minute) that the addition of both the acid and the remainder of the sodium cyanide solution will be completed at the same time. The methyleneaminoacetonitrile begins to separate in white crystals shortly after the addition of the glacial acetic acid has commenced. After all the sodium cyanide solution and acetic acid have been added, the mixture is stirred for one and one-half hours longer; then the precipitate is filtered off, transferred to a beaker, and stirred with 1.5 l. of water. The product is filtered with suction, washed with 500 cc. of water (Note 4), and dried on filter paper. The yield is 410–475 g. (61–71 per cent of the theoretical amount) of a product melting at 129° (Note 5), (Note 6), and (Note 7).
2. Notes
1.
The
formalin should contain no suspended paraformaldehyde. An aqueous
formaldehyde solution of specific gravity 1.078/20° contains 35 per cent
formaldehyde by weight. As pointed out in
Note 1, p. 378, however, technical
formalin contains
methanol, and the
formaldehyde content of technical
formalin is greater than that calculated from the specific gravity of methanol-free
formaldehyde solutions. Accordingly, the figure 18.9 moles for the amount of
formaldehyde present is too low. The exact amount of
formaldehyde present cannot be given, but
formaldehyde in excess is used and the percentage yield is based on the
sodium cyanide.
2.
During the reaction, the temperature should be kept as near 0° as possible and should never rise above 5°. If the temperature goes higher, a heavy oil is sometimes obtained instead of the crystalline product. It is not difficult to maintain the low temperature when the
formaldehyde and
ammonium chloride are cooled to 0° before any of the
sodium cyanide is added.
3.
In order to obtain good yields, the stirring must be vigorous throughout the entire reaction.
4.
With careful washing, 500 cc. of cold water should be sufficient to remove all chlorides.
5.
For most purposes, the product is pure enough as it is obtained from the reaction mixture, but it may be crystallized from water. This recrystallization, however, is attended with considerable loss.
6.
It is suggested that like yields may be obtained by the following modifications: Instead of chilling the
formaldehyde-ammonium chloride mixture from the outside, ice is added during the addition of the
sodium cyanide to keep the temperature down, and the first half of the
sodium cyanide is added during fifteen to twenty minutes. The remainder of the
sodium cyanide and the
acetic acid are added during thirty to forty-five minutes, the temperature being kept below 5° throughout by means of cracked ice. The slight solubility of
methyleneaminoacetonitrile in the liquor makes a larger final volume of no particular disadvantage (W. W. Hartman, private communication).
7.
If a less pure product in lower yield is satisfactory the following procedure, which effects a considerable saving in time, may be used. The mixture of
formaldehyde and
ammonium chloride is cooled by the addition of crushed ice or solid
carbon dioxide, and the
acetic acid is added rapidly. Then, the temperature being maintained below 20° by adding ice or solid
carbon dioxide, the
sodium cyanide solution is added from a dropping funnel over a period of fifteen to twenty minutes. Stirring is continued for fifteen minutes after the
cyanide has been added; then the product is filtered. The yield is 200–267 g. (45–55 per cent of the theoretical amount) of a product melting at 126–128°. (Lawrence H. Amundsen and Ruth Velitzkin, private communication.
1)
3. Discussion
Methyleneaminoacetonitrile can be prepared by the action of
formaldehyde on a mixture of
ammonium chloride, potassium cyanide, and acetic acid,
1 and by the action of
formaldehyde on aminoacetonitrile.
2
This preparation is referenced from:
Appendix
Chemical Abstracts Nomenclature (Collective Index Number);
(Registry Number)
α-Hydroformamine cyanide
acetic acid (64-19-7)
methanol (67-56-1)
ammonium chloride (12125-02-9)
formaldehyde,
formalin (630-08-0)
sodium cyanide (143-33-9)
cyanide (57-12-5)
carbon dioxide (124-38-9)
Methyleneaminoacetonitrile (109-82-0)
formaldehyde-ammonium chloride
ammonium chloride, potassium
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