Hydrogen Hendecanedioate

1 Department of Chemistry, University of California, Berkeley, California. 

METHYL HYDROGEN HENDECANEDIOATE (Undecanedioic acid, monomethyl ester) 

Submitted by Lois J. Durham, Donald J. McLeod, and James Cason.1 Checked by N. J. Leonard, D. H. Dybvig, and K. L. Rinehart, Jr. 

Dimethyl hendecanedioate is prepared by heating 23 g. (0.106 mole) of hendecanedioic acid 2 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 

After the flask has been allowed to stand at room temperature (20-25°) for at least 17 hours (Note 3), the barium salt is collected by suction filtration and washed with about 20 ml. of methanol (Note 4). The moist barium salt is shaken for a few minutes in a separatory funnel with a mixture of 100 ml. of 4 N 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 (Note 5) is distilled through a half-meter column (Note 6). There is essentially no fore-run (see Note 4). The pure half ester is collected at 165-168°/2 mm., weight 14.6-15.7 g. (60-64%), m.p. 44-46° (Note 7). 

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Methyl-2-hexacosenoic acid, 38, 46 Methyl hydrogen adipate, 38, 39 Methyl hydrogen hendecanedioate, 38, 55... 

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