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%).