4494-16-0

112-80-1

4494-16-0

5557-31-3

Oleic acid ((3b), 89 g (90%, 0.315 mol) was transferred via syringe into a 250 mL three-necked round-bottomed flask and vented with nitrogen for 0.5 hours. Subsequently, 1,3-bis(2,4,6-trimethylphenyl)-2-(imidazolidinyl)(dichlorophenylmethylene)(tricyclohexylphosphine)ruthenium (second-generation Grubbs catalyst, 2,267 mg, 0.315 mmol) was added; the reaction required no solvent. The reaction mixture was stirred at 45 °C using a mechanical stirrer and a white precipitate was formed after about 5 min. After the reaction was carried out for 24 h, about 10 mg of the crude product was removed and transferred to a 2 mL dram vial. To the crude diacid product (5b, Equation 1), 1 mL of methanol and two drops of concentrated sulfuric acid were added, and the mixture was heated at 80°C for 0.5 h. (Christie, W.W., Lipid Analysis: Isolation, Separation, Identification and Structural Analysis of Lipids, Oxford, NY Pergamon Press (1982)). The reaction mixture was subsequently quenched with 2 mL of 1M Na2CO3, extracted with ether (3 x 2 mL), and the combined ether layers were washed with water (3 x 2 mL). The organic layer was dried with MgSO4, filtered and the solvent was removed under reduced pressure, and the methylated dicarboxylic acid 5b was characterized by GC/MS (retention time = 14.2 min) to give [M]+ m/z 340 (calculated value, for 5b, [M]+ m/z = 340.26). The remaining crude product was quenched with ethyl vinyl ether (20 mL) and the excess ether was removed under reduced pressure. The residue was recrystallized twice from a mixture of hexane (300 mL) and ethyl acetate (50 mL) to give pure 1,18-octadeca-9-enedioic acid (5b, Equation 1) as a white solid with a melting point of 97.5-98.5°C (literature value 88°C (Van Dam, P.B., et al., J. Am. Oil Chem. Soc., 51. 389-391 (1974)). Isolated yield: 35 g (71%). 1H NMR of 1,18-octadeca-9-enedioic acid (CD3OD, 400 MHz): δ 5.39 (m, -CH=CH-, 2H), 2.28 (t, J=7.2 Hz, -CH2CO2H, 4H), 1.98 (m, 4H), 1.60 (m, 4H), 1.32 (m, 16H) .13C NMR (CD3OD, 100 MHz): δ177.8 (s, CO2H), 131.6 (s, CH=CH), 35.1 (s), 33.7 (s), 30.8 (s), 30.4 (s), 30.3 (s), 30.2 (s), 26.2 (s).