Organic Syntheses, CV 4, 5
Submitted by Richard H. Wiley and O. H. Borum
1.
Checked by R. S. Schreiber and B. D. Aspergren.
1. Procedure
A mixture of
156.6 g. (159 ml., 1.98 moles) of pyridine (Note
1),
239.9 g. (224 ml., 2.35 moles) of acetic anhydride (Note
2), and
35.1 g. (0.39 mole) of vacuum-dried alanine (Note
3) and (Note
4) is heated with stirring (Note
5) on the
steam bath for 6 hours after solution is complete (Note
6). The excess
pyridine and
acetic anhydride, and the
acetic acid, are removed at reduced pressure. The residue is distilled through a
15-cm. column, packed with glass helices, to give
41.5–47.5 g. of crude product, boiling at
110–125°/3 mm. Refractionation gives
41–45 g. (
81–88%) of
3-acetamido-2-butanone; b.p.
102–106°/2 mm.;
nD25 1.4558–1.4561 (Note
7).
2. Notes
1. A commercial
C.P. grade can be used. The checkers used Merck A.R. grade.
2. A commercial grade, 95% minimum assay, can be used. The checkers used Merck A.R. grade.
3. Any good commercial grade material appears to be satisfactory.
4. Reducing the molar ratio of
pyridine or anhydride to the amino acid reduces the yield.
5. Without stirring the yield is
46%.
6. With other amino acids, notably
glycine and
sarcosine, it is necessary to reflux the reactants 1–6 hours.
7. The checkers found it necessary to heat the column to obtain the maximum available product.
3. Discussion
This preparation is referenced from:
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