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).