Submitted by H. T. Clarke and S. M. Nagy.
Checked by W. E. Bachmann and Wayne Cole.
1. Procedure
To
350 ml. of anhydrous methanol contained in a
1-l. three-necked round-bottomed flask, to which is attached a reflux condenser protected by a drying tube, is added
20 g. (0.87 gram atom) of sodium (Note
1) in large pieces. The reaction is kept under control by cooling the flask in a pan of ice water. To the resulting solution of
sodium methoxide is added a solution (Note
2) of
61 g. of hydroxylamine hydrochloride (0.88 mole) in 20 ml. of water; during the addition the mixture is swirled in order to avoid spattering. After 20 minutes the mixture is cooled to 0° and filtered with suction. The
sodium chloride is washed with
350 ml. of anhydrous methanol. The combined filtrate and washings are warmed to 65° in a
3-l. round-bottomed flask, and a solution of
100 g. of finely powdered commercial crystalline glucose monohydrate (0.50 mole) in 200 ml. of warm 25% aqueous methanol is added, with stirring. The resulting solution is held at 65° for 2 hours and then concentrated under reduced pressure until no further distillate is obtained; the residue weighs 155–160 g. The resulting syrup (Note
3) is diluted with
300 ml. of methanol and again distilled, and this process is repeated once (Note
4).
A mixture of
100 g. of powdered, anhydrous sodium acetate and
677 ml. of 90% acetic anhydride (Note
5) is heated on a
steam bath in a 3-l. round-bottomed flask under an
efficient reflux condenser. Without interrupting the heating a solution of the syrupy
glucose oxime in 50 ml. of glacial acetic acid and
100 ml. of cold acetic anhydride is added through a
dropping funnel to the hot mixture (Note
6); this requires about 1 hour (Note
7). Heating is continued for another hour, and the bulk (380–420 ml.) of the
acetic acid and any unchanged
acetic anhydride is distilled under reduced pressure from a
water bath. The residue is immediately stirred into 2 l. of cold water, stirred occasionally during the first 3 hours, and allowed to stand overnight.
After the mixture has been chilled to 0°, the brown, crystalline mass is filtered with suction and washed with 500 ml. of water. The solid is dissolved in
300 ml. of hot 95% ethanol, and the solution is heated with
10–15 g. of Norit for 5 minutes and filtered with suction. The filtrate is gradually cooled to 0°; the crystals are filtered with suction and washed with
20 ml. of cold ethanol. The weight of the first crop is
90–93 g. A second crop is obtained by concentrating the mother liquor under reduced pressure to 25 ml., boiling the solution with
Norit, filtering, and chilling the filtrate to 0°. The total yield of colorless
pentaacetyl d-glucononitrile melting at
82.5–83.5° is
95–96 g. (
50%).
2. Notes
1. In preparing free
hydroxylamine, a little less than the theoretical amount of
sodium is employed to avoid the presence of free alkali in the reaction mixture.
3. The isolation of
glucose oxime is unnecessary in this preparation.
4. The distillation with
methanol serves to remove water almost completely.
5. If
acetic anhydride of a higher concentration is available, correspondingly smaller quantities may be employed.
6. The viscous, syrupy
glucose oxime dissolves with difficulty, and it may be necessary to warm the mixture slightly. If this is done, a pan of ice water should be at hand in order to cool the mixture should the temperature begin to rise rapidly.
7. In the process described in the literature, the oxime,
sodium acetate, and
acetic anhydride are allowed to react without dilution, a condition which frequently leads to an uncontrollably violent reaction.
3. Discussion
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