Bromine is added dropwise with stirring to 35 g. (0.118 mole) of methyl oleate (Note 1) in a 500-ml. round-bottomed flask. The mixture is kept below 50° throughout the addition, which is continued until a slight excess of bromine is present; approximately the theoretical amount (18.9 g.) is decolorized. Methyl oleate (2–3 drops) is then added until the bromine color just disappears. n-Amyl alcohol (50 ml.) (Note 2) and potassium hydroxide pellets (40 g., 0.61 mole assuming 85% purity) are added to the flask, and the mixture is heated under reflux for 4 hours in an oil bath at 150°. Then approximately 50 ml. of the n-amyl alcohol is distilled at atmospheric pressure (Note 3). The residue on cooling solidifies into a tan-colored mass. Phenolphthalein is added as an indicator, the mixture is cooled in an ice bath, and concentrated hydrochloric acid is added in portions until the red color disappears but reappears on stirring of the viscous mass. This process is continued until the mixture remains colorless. Water (approximately 200 ml.) is added, and the mixture is allowed to come to room temperature. Concentrated hydrochloric acid is added until the mixture is acid to methyl orange. The mixture is again cooled in an ice bath; the oily layer solidifies into a wax, and the acidic water solution is decanted. The wax is dissolved in 100 ml. of 95% ethanol at room temperature, and water is added until the solution becomes turbid. The mixture is heated on a steam bath until a clear solution is formed, and then it is cooled in an ice bath and stirred while the product crystallizes. The semisolid mass is filtered, and the product is recrystallized three times from an ethanol-water mixture. After drying in a vacuum desiccator the yield is 11–14 g. (33–42%), m.p. 46–46.5°; neutral equivalent 279.7–281.4 (calcd. 280.4); hydrogen absorbed by catalytic reduction 94–100%.