Dimethyl dioate (CAS NO.: ), which is also known as , di, could be produced through the following synthetic routes.

To 500 ml. of absolute methanol in a 1-l. electrolytic (tall form) beaker is added 1.1 g. (0.05 g. atom) of clean sodium metal. After solution of the sodium, 216 g. (1.0 mole) of methyl hydrogen sebacate is dissolved in the sodium methoxide solution. A magnetic stirring bar is placed in the beaker which is then fitted with a large neoprene stopper holding a platinum sheet anode, 12 cm.2 in area; and two platinum sheet cathodes, approximately 5.3 cm.2 in area, spaced equidistantly on either side of the anode at a distance of approximately 1.5 cm.. The stopper is also provided with a stoppered entry tube and an efficient reflux condenser.

The electrodes are connected to a suitable variable source of direct current, the magnetic stirrer is started, and a potential of about 50 volts is applied. This results in a current flow of 1–2 amperes. The solution soon comes to boiling; the voltage is then regulated so that a rapid reflux is maintained.

Completion of the run, after 30–40 hours, is indicated when a few drops of the solution show an alkaline reaction to phenolphthalein. No harm is done if the electrolysis is carried a few hours beyond this point; however, after excessively long periods, formation of polymeric material lowers the yield and renders purification of the product rather troublesome.

Upon completion of the reaction the solution is acidified with acetic acid, and the solvent removed under reduced pressure. The residue is dissolved in about 1.4 l. of ether and filtered into a 2-l. separatory funnel through fluted paper. After the ether solution has been washed with two 300-ml. portions of 5% aqueous sodium bicarbonate solution, the ether is removed on a steam bath. The residue is dissolved in about 1.5 l. of warm methanol, and the solution is allowed to cool to room temperature. The crystallized product is collected by suction filtration on a Büchner funnel and pressed well. The product is rather waxy and is best washed by transferring it to a beaker and stirring thoroughly with about 150 ml. of cold methanol. The white crystals are then collected and pressed well again. If the filtrate is colored, the crystals are washed again with a smaller quantity of methanol. The combined filtrate and washings are concentrated to one-half the original volume and chilled in ice to yield a few grams of additional product of the same melting point. The combined lots are dried in a vacuum desiccator. The yield amounts to 116–126 g. (68–74%) of white, microcrystalline dimethyl octadecanedioate, m.p. 57–58°.