Methyl hydrogen hendecanedioate (CAS NO.: ), which is also known as dioic acid, , could be produced through the following synthetic routes.

Dimethyl hendecanedioate is prepared by heating 23 g. (0.106 mole) of hendecanedioic acid (p.510) under reflux for 2 hours with a solution of 8 ml. of concentrated sulfuric acid in 80 ml. of methanol. After the reaction mixture has been diluted with 3 volumes of water, it is extracted with two 75-ml. portions of benzene. The benzene extracts are washed successively with 250-ml. portions of water, 5% aqueous sodium carbonate solution, and water. After the benzene has been removed under reduced pressure, the residue is transferred to a 250-ml. Erlenmeyer flask containing 127 ml. of a 0.915N solution of barium hydroxide (0.058 mole) in commercial anhydrous methanol. The flask is immediately closed with a soda-lime tube and swirled to mix the solution. The barium salt of the half ester begins to precipitate after about 2 minutes.

After the flask has been allowed to stand at room temperature (20–25°) for at least 17 hours, the barium salt is collected by suction filtration and washed with about 20 ml. of methanol. The moist barium salt is shaken for a few minutes in a separatory funnel with a mixture of 100 ml. of 4N hydrochloric acid and 100 ml. of ether. The aqueous layer, together with any precipitated barium chloride, is removed and extracted again with 100 ml. of ether. The two ether extracts are combined and washed with three 100-ml. portions of water, the solvent is removed, and the residue is distilled through a half-meter column. There is essentially no fore-run. The pure half ester is collected at 165–168°/2 mm., weight 14.6–15.7 g. (60–64%), m.p. 44–46°.