Org. Synth. 1947, 27, 41
DOI: 10.15227/orgsyn.027.0041
Glycolonitrile
Submitted by Roger Gaudry
Checked by C. F. H. Allen and J. A. VanAllan.
1. Procedure
This preparation should be carried out under a good hood since poisonous hydrogen cyanide may be evolved.
In a
1-l. three-necked flask, fitted with a stirrer, thermometer for reading low temperatures, and a dropping funnel, and surrounded by an ice-salt bath, is placed a solution of
130 g. (2.0 moles) of potassium cyanide in 250 ml. of water. With stirring, a solution of
170 ml. (2.0 moles) of commercial 37% formaldehyde solution
1 and 130 ml. of water is admitted slowly from the dropping funnel at such a rate that the temperature never rises above 10° (about 40 minutes is required). After 10 minutes' standing,
230 ml. of dilute sulfuric acid (57 ml. of concentrated sulfuric acid, sp. gr. 1.84, in 173 ml. of water) is added with stirring, the same low temperature being maintained. A copious precipitate of
potassium sulfate is formed. The
pH of the solution is then about 1.9. A
5% potassium hydroxide solution is then added, dropwise, and with cooling, until the
pH is about 3.0 (determined either by means of a
pH meter or tropaeolin 00 paper); about 4 ml. of the solution is required. The flask is then removed from the
cooling bath,
30 ml. of ether is added, and the mixture is well shaken. The salt is removed by filtration, using a
14-cm. Büchner funnel, and washed with
30 ml. of ether. The filtrate is poured into a
1-l. continuous ether extractor2 and extracted for 48 hours with
300 ml. of ether (Note 1). The
ether extract is dried for 3–4 hours over
15 g. of anhydrous calcium sulfate (Drierite) (Note 2) and filtered.
Ten milliliters of absolute ethanol is added to the filtrate, and the
ether is removed on a
steam bath (Note 3). The residue is distilled under reduced pressure using a
flask having a Vigreux side arm. After a small (2–3 ml.) fore-run, the
glycolonitrile distils smoothly at
86–88°/8 mm. (
102–104°/16 mm.). The yield of pure
glycolonitrile (Note 4) amounts to
86.5–91 g. (
76–80%).
2. Notes
1.
It is impractical to extract more than 40–45% of the nitrile without using a continuous ether extractor. A slightly lower yield is obtained if the extraction is continued for only 24 hours. The reaction mixture may be extracted in portions if the available flask is smaller than that specified.
2.
Anhydrous
sodium sulfate can be used equally well, but its drying action is slower, at least 24 hours being advisable.
3.
If the
ethanol is omitted, the nitrile shows a strong tendency to polymerize during the removal of the
ether, especially when most of the
ether has distilled.
4.
The
ethanol serves as a preservative before and after the distillation.
Glycolonitrile obtained without the use of
ethanol usually cannot be kept more than a few days; it sometimes turns brown within 24 hours. Some samples of ethanol-stabilized
glycolonitrile have been preserved in sealed bottles for 2 years, whereas other samples polymerized in a few months.
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3. Discussion
Glycolonitrile has usually been prepared by the interaction of
formaldehyde and an alkali cyanide in aqueous solution
3 of which the procedure outlined is a modification. A more recent development is the cyanohydrin interchange method.
4,5 Glycolonitrile has also been prepared by a catalytic oxidation of
methanol and
ammonia in the vapor phase.
6
Appendix
Chemical Abstracts Nomenclature (Collective Index Number);
(Registry Number)
ethanol (64-17-5)
sulfuric acid (7664-93-9)
ammonia (7664-41-7)
methanol (67-56-1)
ether (60-29-7)
formaldehyde (50-00-0)
potassium sulfate (37222-66-5)
hydrogen cyanide (74-90-8)
sodium sulfate (7757-82-6)
potassium cyanide (151-50-8)
calcium sulfate (7778-18-9)
potassium hydroxide (1310-58-3)
Glycolonitrile (107-16-4)
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