In a 5-l. flask, fitted with a stirrer, a reflux condenser, and a dropping funnel, is placed 1 kg. (1266 cc.) of absolute ethyl alcohol (p. 249 and p. 259); 92 g. (4 atoms) of sodium, cut into strips, is then added through the condenser at such a rate that the alcohol does not boil too vigorously. When all the sodium is in solution, the flask is cooled and 800 g. (754 cc., 5 moles) of diethyl malonate added through the condenser, with stirring. The mixture is warmed gently on the steam bath and 700 g. (658 cc., 4.1 moles) of diethyl fumarate (Note 1) added from the dropping funnel. During this addition the solution is kept boiling gently, heat being applied if necessary (Note 2). The mixture is boiled for one hour after the diethyl fumarate has been added. It is then cooled and 250 g. (238 cc., 4.2 moles) of glacial acetic acid is added.

Most of the alcohol is distilled off under slightly reduced pressure on the steam bath and the residue is poured into sufficient distilled water to dissolve all the solid. The water layer is separated and extracted four times with carbon tetrachloride, which is added to the ester layer. The ester-carbon tetrachloride mixture is washed twice with water and the water washings extracted once with carbon tetrachloride. The carbon tetrachloride is distilled off under atmospheric pressure through a column, the moisture being carried over simultaneously.

The residue is then distilled under reduced pressure, when the ethyl propane-1,1,2,3-tetracarboxylate comes over at 182–184°/8 mm. The yield is 1261–1273 g. (93–94 per cent of the theoretical amount).