A solution of
1 kg. of sucrose in 9 l. of water is placed in a
20-l. bottle provided with a gas trap. A paste of baker's yeast (Note
1) is made by breaking up 1 kg. of yeast and gradually stirring in 1 l. of water. This is then added to the sugar solution and the mixture is allowed to stand at room temperature until a lively evolution of gas starts (from one to three hours). To the vigorously fermenting solution
100 g. (1.35 moles) of freshly prepared acetol (p. 5) is added, and the mixture is allowed to stand at room temperature until the reaction subsides (Note
2). The bottle is then transferred to an
incubator at 32°, when the fermentation recommences. At the end of three days the reaction is generally completed, and the solution when tested with
Fehling's reagent gives a negligible test for reducing sugars.
At this point 20–30 g. of short glass fiber or asbestos is added and the yeast is filtered by suction. The filtrate is concentrated to a thick syrup under diminished pressure on a
water bath, the temperature being kept below 40° (Note
3). The residue (about 200 cc.) is taken up in a mixture of
400 cc. of absolute alcohol and
100 cc. of dry ether (Note
4). The precipitate formed is removed by centrifuging, the supernatant liquid is decanted, and the residue is extracted with a mixture of
200 cc. of 98.5 per cent alcohol and
100 cc. of dry ether (Note
5). The combined
alcohol-
ether solutions are concentrated under diminished pressure at 35–40° to a thick syrup. The residue is again taken up in a mixture of
400 cc. of 98.5 per cent alcohol and
100 cc. of dry ether and centrifuged (Note
5). The supernatant liquid is concentrated under diminished pressure and distilled from a
modified Claisen flask. The yield of the crude product boiling at
86–91°/12 mm. is approximately
100 g. The crude material is refractionated and collected at
88–90°/12 mm. or
187–189°/760 mm. The final product (Note
4) is a colorless liquid having a density 1.04 and specific rotation
[α]20D = −15.0°. The yield is
50–60 g. (
49–58 per cent of the theoretical amount) (Note
6).