Org. Synth. 1954, 34, 51
DOI: 10.15227/orgsyn.034.0051
ETHYL ENANTHYLSUCCINATE
[Succinic acid, heptanoyl-, diethyl ester]
Submitted by Tracy M. Patrick, Jr. and Floyd B. Erickson
1.
Checked by T. L. Cairns and R. D. Cramer.
1. Procedure
A mixture of
228 g. (2.0 moles) of enanthaldehyde (Note 1) and
172 g. (1.0 mole) of ethyl maleate (Note 2) is placed in a
jacketed flask (
Fig. 9)
(Note 3) with
condensers attached to the flask and the jacket openings. The jacket is charged with
trichloroethylene (Note 4), which is heated to reflux, and, when the reaction mixture reaches 84–85°,
0.5 g. of benzoyl peroxide is added to the mixture through the condenser. After 3–8 hours an additional
0.5-g. portion of benzoyl peroxide is added, and heating is continued for a total of 18–24 hours
(Note 5).
Fig. 9.
The reaction mixture is distilled through a short (8- to 12-in.) Vigreux column to give 108–111 g. of recovered enanthaldehyde, b.p. 64–65°/38 mm.; 6–16 g. of an intermediate fraction, b.p. 82–128°/1 mm.; and 202–216 g. (71–76% yield) of ethyl enanthylsuccinate, b.p. 119–122°/0.7 mm., nD25 1.4392–1.4398 (Note 6), (Note 7), and (Note 8).
2. Notes
1.
Good-quality enanthaldehyde such as the white label grade supplied by Eastman Kodak Company was distilled before use. It is best stored in a
brown bottle under
nitrogen for protection against oxidation.
2.
Ethyl maleate from Commercial Solvents Corporation, Terre Haute, Indiana, was distilled before use.
Ethyl fumarate can be used also, but the yield of product is lower since a much greater proportion of high-boiling compounds is obtained. Al-dehydes do not undergo free-radical addition to
maleic anhydride under these conditions.
3.
Although this piece of apparatus is not essential, it provides a convenient means of controlling the temperature for a mildly exothermic reaction which must be carried out overnight without close supervision. The submitters carried out one experiment in an ordinary apparatus heated by a mantle. The poorer temperature control (70–91°) resulted in a yield of only 44%.
4.
Any other stable liquid having a boiling point in the neighborhood of 80–90° could be substituted for
trichloroethylene.
5.
The reaction time is not critical. For the sake of convenience the reaction can be started early in the day, the second portion of peroxide added before leaving in the evening, and heating discontinued upon arrival the following morning.
6.
The submitters collected material boiling in the range
128–150°/1 mm. and found this product to be satisfactory for the preparation of
γ-oxocapric acid (Note 7).
7.
The submitters state that
ethyl enanthylsuccinate can be hydrolyzed and decarboxylated to
γ-oxocapric acid. The reaction is carried out by heating 57 g. of the keto ester with a solution of
140 ml. of concentrated sulfuric acid in 250 ml. of water. The mixture is stirred while the
ethanol is removed gradually by distillation over a period of 3 hours. The acid is taken up in
benzene, extracted from the
benzene with aqueous alkali, and liberated from the alkaline solution by acidification with concentrated
hydrochloric acid. After recrystallization from
50% ethanol about
29 g. (
78% yield) of
γ-oxocapric acid is obtained as colorless crystals, m.p.
69–70°.The submitters also state that γ-caprilactone can be prepared by hydrogenation of 50 g. of γ-oxocapric acid in 150 ml. of ethanol over 5 g. of Raney nickel at 135° and 1000 p.s.i. Filtration and distillation gives about 38 g. (83% yield) of γ-caprilactone, b.p. 109–110°/2.5 mm., nD25 1.4470.
8.
A number of other acylsuccinic esters can be prepared in a similar fashion from the appropriate saturated aliphatic aldehydes and maleic esters.
2,3 The procedure is equally adaptable to the preparation of α-acyltricarballylic esters from aldehydes and aconitates
2. Good temperature control (80–90°) is most important for success in these reactions.
3. Discussion
Ethyl enanthylsuccinate has been prepared by the free-radical addition of
enanthaldehyde to
ethyl maleate.
2
Appendix
Chemical Abstracts Nomenclature (Collective Index Number);
(Registry Number)
γ-caprilactone
ethanol (64-17-5)
sulfuric acid (7664-93-9)
hydrochloric acid (7647-01-0)
Benzene (71-43-2)
nitrogen (7727-37-9)
Raney nickel (7440-02-0)
ethyl fumarate (2459-05-4)
benzoyl peroxide (94-36-0)
maleic anhydride (108-31-6)
trichloroethylene (79-01-6)
Ethyl enanthylsuccinate
Succinic acid, heptanoyl-, diethyl ester (41117-78-6)
enanthaldehyde (111-71-7)
ethyl maleate (3990-03-2)
γ-oxocapric acid
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