Dimethyl hexadecane-1 .• 16-dicarboxylate

Myristic acid from hexanoic acid and methyl hydrogen sebacate). Dissolve 23 -2 g. of redistilled hexanoic acid (re caproic acid), b.p. 204-6-205-5°/760 mm., and 21-6 g. of methyl hydrogen sebacate in 200 ml. of absolute methanol to which 0 13 g. of sodium has been added. Electrolyse at 2 0 amps., whilst maintaining the temperature between 30° and 40°, until the pH is about 8 0 (ca. 6 hours). Neutralise the contents of the electrolysis cell with a little acetic acid and distil off the methyl alcohol on a water bath. Dissolve the residue in 200 ml. of ether, wash with three 50 ml. portions of saturated sodium bicarbonate solution, once with water, dry with anhydrous magnesium sulphate, and distil with the aid of a fractionating column (see under Methyl hydrogen adipate). Collect the re-decane at 60°/10 mm. (3 0 g.), the methyl myristate at 158-160°/ 10 mm. (12 5g.) and dimethyl hexadecane-1 16-dicarboxylate at 215-230°/ 7 mm. (1 -5 g.)... 

Hexadecane-1 16-dicarboxylie acid. Dissolve 31 5 g. of methyl hydrogen sebacate in 140 ml. of absolute methanol to which 0-4 g. of sodium lias been added. Electrolyse at 2 0 amps, until the pH of the electrolyte is 7 8-8 0 (3-5-4 hours). Work up as described for Sebacic acid. Upon distillation, an unsaturated ester passes over at 111-113°/ 20 mm. (4-6 g.), followed by dimethyl hexadecane-1 16-dicarboxylate at 212-219°/4 mm. (mainly at 214-215°/4 mm.), m.p. 56° (16-5 g.). 

Reflux 6 8 g. of the dimethyl ester with a solution of 3 2 g. of sodium hydroxide in 150 ml. of 80 per cent, methanol for 2 hours on a water bath. When cold, filter oflF the solid and wash it with a little cold methanol. Dissolve the solid in 350 ml. of warm water, add concentrated hydrochloric acid to the solution at 60° until acidic to litmus, filter off the precipitated acid, wash with a little water and dry at 100°. The resulting hexadecane-1 16 dicarboxylic acid, m.p. 122°, weighs 5-3 g. Recrystallisation from absolute methanol raises the m.p. to 124 -5°. 

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