In a
2-l. three-necked flask, fitted with a
mercury-sealed stirrer,
reflux condenser, and
dropping funnel, is placed
500 cc. of absolute ethyl alcohol (Note
1), and
23 g. (1 gram atom) of cleanly cut sodium is added in portions. When the
sodium has dissolved the solution is cooled to 60°, and
146 g. (1 mole) of ethyl oxalate (Note
2) is added in a rapid stream through the funnel with vigorous stirring. This is washed down with a small quantity of
absolute alcohol and is followed immediately by the addition of
175 g. (1.06 moles) of ethyl phenylacetate. Stirring is discontinued at once, the reaction flask is lowered from the stirrer, and a
2-l. beaker is made ready. Within four to six minutes after the
ethyl phenylacetate has been added crystallization sets in. The contents of the flask are transferred immediately to the beaker at the first sign of crystallization, which is nearly instantaneous.
The nearly solid paste of the sodium derivative is allowed to cool to room temperature and then stirred thoroughly with
800 cc. of dry ether. The solid is collected by suction and washed repeatedly with dry
ether. The
phenyloxaloacetic ester is liberated from the sodium salt with dilute
sulfuric acid (29 cc. of concentrated sulfuric acid in 500 cc. of water). The almost colorless oil is separated, and the aqueous layer is extracted with three
100-cc. portions of ether, which are combined with the oil. The ethereal solution is dried over anhydrous
sodium sulfate, and the
ether is distilled. The residual oil, contained in a
modified Claisen flask having a fractionating side arm, is heated under a pressure of about 15 mm. in a
bath of Wood's metal. The temperature of the bath is brought gradually to 175° and kept there until the evolution of
carbon monoxide is complete. During this process the heating is momentarily discontinued in the event of a temporary increase in pressure. At the end of the reaction (five to six hours) the oil which has distilled is returned to the flask, and the
ethyl phenylmalonate is distilled at reduced pressure. The fraction boiling at
158–162°/10 mm. weighs
189–201 g. (
80–85 per cent of the theoretical amount).