Org. Synth. 1962, 42, 28
DOI: 10.15227/orgsyn.042.0028
t-BUTYL ACETOACETATE
[Acetoacetic acid, tert-butyl ester]
Submitted by Sven-Olov Lawesson, Susanne Gronwall, and Rune Sandberg
1.
Checked by William G. Dauben and Richard Ellis.
1. Procedure
Caution! This preparation should be conducted in a hood to avoid exposure to diketene, which is toxic and which may irritate mucous tissues such as those of the eyes; the use of safety goggles is recommended.
A 500-ml. three-necked flask is equipped with a sealed mechanical stirrer, a dropping funnel, and a two-armed addition tube, one arm of which bears a reflux condenser and the other arm of which is fitted with a thermometer. t-Butyl alcohol (79 g., 1.07 moles) (Note 1) is added to the flask and the thermometer arranged so that its bulb is immersed in the liquid but out of the path of the stirrer. The flask is heated by means of an electric mantle until the temperature of the liquid is 80–85°, and the mantle then is removed. Anhydrous sodium acetate (0.4 g., 4.8 mmoles) is added with stirring, and then 96 g. (1.14 moles) of diketene (Note 2) is added dropwise over a period of 2.5 hours. The temperature of the solution drops to 60–70° during the first 15 minutes and then increases slowly to 110–115°. When all the diketene is added, the reaction subsides and, after the resulting brown-black solution is stirred for an additional 30 minutes, the product is distilled immediately under reduced pressure through a short column. After a small fore-run, the yield of t-butyl acetoacetate, b.p. 85°/20 mm. (Note 3), nD20 1.4200–1.4203, is 127–135 g. (75–80%) (Note 4).
2. Notes
1.
Eastman Kodak white label grade is used without further purification.
2.
The submitters used material directly as supplied by Dr. Theodor Schuchardt and Co., Munich, Germany. The checkers used material directly as supplied by Aldrich Chemical Co., Milwaukee, Wisconsin.
3.
The still residue is
dehydroacetic acid.
4.
In a run five times the size described, the submitters report that the reaction goes in the same manner and in
85–92% yield.
3. Discussion
t-Butyl acetoacetate has been prepared by self-condensation of
t-butylacetate.
2,3 The described procedure is based upon the method of Treibs and Hintermieier.
4
The present preparation employs a method of considerable scope and is illustrative of a general method of preparing esters of
acetoacetic acid; it gives much better yields, is considerably less laborious than other methods for the preparation of
t-butyl acetoacetate, and appears to be the most convenient as starting materials are easily accessible. The title compound is of specific interest since the
t-butoxy carbonyl group may be removed simply by heating the compound with catalytic amounts of
p-toluenesulfonic acid. For instance, a new method has been developed for the preparation of acyloins by introducing the benzoyloxy group into
t-butyl acetoacetate, followed by
t-butoxy carbonyl-elimination and hydrolysis.
5 Using a similar technique and starting from
t-butyl acetoacetate, levulinic esters,
6 δ-ketonitriles,
7 1-methylcyclohexene-1-on-3,
8 α,β-unsaturated ketones,
9 and piperiton and related compounds
10 have been prepared.
This preparation is referenced from:
Appendix
Chemical Abstracts Nomenclature (Collective Index Number);
(Registry Number)
sodium acetate (127-09-3)
diketene (674-82-8)
Dehydroacetic acid (520-45-6)
t-butyl alcohol (75-65-0)
acetoacetic acid (541-50-4)
p-toluenesulfonic acid (104-15-4)
t-BUTYL ACETOACETATE,
Acetoacetic acid, tert-butyl ester (1694-31-1)
t-butylacetate
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