Organic Syntheses, CV 2, 305
Submitted by E. J. Witzemann, Wm. Llloyd Evans, Henry Hass, and E. F. Schroeder.
Checked by Frank C. Whitmore and Harry T. Neher.
1. Procedure
A mixture of
50 g. (0.3 mole) of dl-glyceraldehyde acetal (p. 307) and
500 cc. of 0.1 N sulfuric acid is allowed to stand for one week at about 20° (Note
1).
Thirty cubic centimeters of glacial acetic acid is added; the mixture is neutralized carefully with
barium hydroxide solution (Note
2), stirred with
5 g. of decolorizing carbon, and filtered. The filtrate is evaporated at 10 mm. pressure (Note
3). When no more water can be removed, the residue is treated with an equal volume of
absolute alcohol to hasten crystallization. The crystals are collected on a filter and dried in a
vacuum desiccator over
soda-lime and calcium chloride. The yield of product melting at
137–139° is
22 g. (
80 per cent of the theoretical amount).
2. Notes
1. During the entire preparation, including the evaporation, the temperature should be kept below 30°. If this precaution is rigidly observed, the
glyceraldehyde crystallizes readily.
3. The use of 10 mm. instead of 20 mm. pressure for the evaporation improves the quality of the
glyceric aldehyde, making the difference between a syrup which may or may not crystallize and a product which crystallizes even from the concentrated solution.
3. Discussion
This preparation is referenced from:
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