Org. Synth. 1937, 17, 54
DOI: 10.15227/orgsyn.017.0054
ETHYL ETHOXALYLPROPIONATE
[Oxalacetic acid, methyl-, diethyl ester]
Submitted by Richard F. B. Cox and S. M. McElvain.
Checked by Reynold C. Fuson and William E. Ross.
1. Procedure
Sixty-nine grams (3 gram atoms) of sodium is powdered under
xylene in a
3-l. three-necked flask. The mixture is cooled, the
xylene is decanted, and the
sodium is washed twice with small portions of dry
ether.
One liter of absolute ether is then added to the powdered
sodium. The flask is fitted with a
mercury-sealed stirrer, an
efficient reflux condenser, and a
dropping funnel, the condenser and the funnel being protected from moisture with
calcium chloride tubes.
One hundred and thirty-eight grams (175 cc., 3 moles) of absolute ethyl alcohol is added drop by drop through the funnel
(Note 1). After the alcohol has been added and there is no unchanged
sodium (as evidenced by cessation of boiling) the flask is immersed in an
ice-water bath, and a mixture of
306 g. (3 moles) of ethyl propionate and
438 g. (3 moles) of ethyl oxalate (Org. Syn. Coll. Vol. I, 1941, 261) is added slowly through the
dropping funnel (Note 2).
After the ester mixture has been added, the stirrer is removed and the condenser set for downward distillation. The ether and the alcohol formed in the reaction are removed by heating on a water bath (Note 3). The residue, which usually solidifies upon cooling, is treated with 600 cc. of cold, 33 per cent acetic acid solution. The mixture is allowed to stand for several hours with occasional shaking in order to decompose the sodium derivative completely, and the product is extracted with four 500-cc. portions of ether. The ether solution is washed with 1 l. of water, with two 500-cc. portions of 10 per cent sodium bicarbonate solution, and finally with 1 l. of water. The ether is then removed by distillation, using a steam bath. The residue is fractionated through an efficient column (Note 4). The portion boiling at 114–116°/10 mm. is collected. The yield is 363–425 g. (60–70 per cent of the theoretical amount).
2. Notes
1.
The addition of the alcohol takes from four to six hours, depending on the efficiency of the condenser and stirrer.
2.
The addition of the ester mixture should be slow enough so that the
ether does not reflux. This addition takes two to three hours.
3.
When most of the alcohol has distilled, a yellow scum forms on the surface of the red, viscous liquid. The distillation is stopped at this point. When the solution is cooled, the sodium derivative crystallizes with considerable expansion in volume.
4.
No appreciable decomposition of the ethoxalyl ester into
ethyl methylmalonate takes place when the distillation is carried out at 10 mm. To prevent overheating, the use of an oil bath and a heated column is recommended.
3. Discussion
Ethyl ethoxalylpropionate has been prepared by the Claisen condensation of
ethyl oxalate with
ethyl propionate1 as above, and by the alkylation of
ethyl ethoxalylacetate.
1
This preparation is referenced from:
Appendix
Chemical Abstracts Nomenclature (Collective Index Number);
(Registry Number)
ETHYL ETHOXALYLPROPIONATE
ethyl ethoxalylacetate
ethyl alcohol (64-17-5)
acetic acid (64-19-7)
ether (60-29-7)
sodium bicarbonate (144-55-8)
sodium (13966-32-0)
xylene (106-42-3)
Ethyl oxalate
Oxalacetic acid, methyl-, diethyl ester
ethyl propionate (105-37-3)
Ethyl methylmalonate
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