Diethyl trans-Δ⁴-Tetrahydrophthalate could be produced through many synthetic methods.

A 300-ml. pressure reaction vessel, capable of withstanding at least 250 p.s.i. at 125° is charged with 60.0 g. (0.508 mole) of 3-sulfolene, 86.0 g. (82.0 ml., 0.500 mole) of diethyl fumarate, and 1.0 g. of hydroquinone. Commercial absolute ethanol (90 ml.) is added, and the mixture stirred until most of the solid is dissolved. The vessel is sealed, heated slowly to 105–110°, and maintained at that temperature 8–10 hours. The vessel is then allowed to cool to room temperature, opened, and the yellowish, fluid reaction mixture is poured into a 1-l. Erlenmeyer flask.

The liquid is stirred vigorously, and a solution of 60.0 g. (0.566 mole) of sodium carbonate in 350 ml. of water is added to the flask as rapidly as the concomitant evolution of carbon dioxide will permit. Stirring is continued for about 15 minutes after the addition is complete. The original reaction vessel is rinsed with 200 ml. of petroleum ether (b.p. 60–75°), the rinse is added to the Erlenmeyer flask containing the product, and the mixture is stirred for about 10 minutes at a rate sufficient to achieve homogenization. The resulting loose emulsion is quickly transferred to a 1-l. separatory funnel and allowed to separate; the lower (aqueous) phase is drawn off into the original Erlenmeyer flask and the upper (organic) layer containing the desired product is transferred to a 500-ml. flask. In exactly the same manner the aqueous phase is extracted by vigorous stirring with two 100-ml. portions of petroleum ether, the organic layers being added to the retention flask. The combined organic layers are transferred from the flask to the same separatory funnel and shaken once with 100 ml. of cold, 5%, aqueous sodium carbonate and twice with 50-ml. portions of cold water. The organic layer is returned to the retention flask, dried over 10 g. of anhydrous magnesium sulfate, filtered by gravity, concentrated with a rotary evaporator, and distilled under reduced pressure through a Vigreux column, yielding 75–82 g. (66–73%, based on diethyl fumarate) of the product, b.p. 129–132° (5 mm.), n²⁵D 1.4565–1.4570, d²⁵4 1.0584–1.0589.