Organic Syntheses, CV 3, 434
Submitted by Chester M. McCloskey and George H. Coleman.
Checked by C. S. Hamilton, Robert Angier, and Ivan Baumgart.
1. Procedure
A solution of
82.2 g. (0.2 mole) of acetobromoglucose (p. 11) (Note
1) in
125 ml. of dry acetone (Note
2) in a
250-ml. flask is cooled to 0° in an
ice bath. To the cold solution is added 2.3 ml. of water and then
46.5 g. (0.17 mole) of silver carbonate (Note
3) in small portions in the course of 15 minutes. The mixture is shaken well during the addition and for 30 minutes longer (Note
4). The mixture is then warmed to 50–60° and filtered. The mass of silver salts is washed with
65 ml. of dry acetone (Note
5), removed from the funnel, warmed in a flask with
65 ml. more of acetone, filtered, and washed again on the funnel.
The combined filtrates are concentrated under reduced pressure in a
500-ml. filter flask (Note
6) until most of the solution is filled with crystals. The mixture is warmed to dissolve the crystals, the solution is poured into a
600-ml. beaker, and an equal volume of absolute
ether and a similar volume of
ligroin are added. The resulting solution is cooled in a freezing mixture with gentle stirring. The crystals of the tetraacetate form quickly and after about 10 minutes are filtered and air-dried. The crystals so obtained melt at
132–134° (Note
7). If a purer product is required, the product is dissolved in
acetone, and
ether and
ligroin are added to the solution in the manner described. The yield of once-crystallized product melting at
132–134° is
52–56 g. (
75–80%).
2. Notes
4. At the end of this time, evolution of
carbon dioxide should no longer be appreciable. The time required for the reaction depends largely on the agitation of the
silver carbonate. In large runs mechanical stirring is required.
5. Anhydrous chemicals are used throughout as the presence of any appreciable amount of water interferes with the crystallization of the tetraacetate.
6. The solution is not heated during the concentration, and thus the temperature is maintained below that of the room by the evaporation of the solvent. If a capillary is used it should be equipped with a
drying tube.
3. Discussion
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