Ultrasound-assisted oxidative cleavage of acetylenic and ethylenic bonds in unsaturated fatty esters with potassium permanganate.

The effect of ultrasound on the oxidation of unsaturated fatty esters was investigated. Unsaturated fatty esters containing acetylenic or olefinic bonds or both were oxidatively cleaved with KMnO4 in aqueous acetic acid (AcOH/H2O, 1:1, vol/vol for olefinic fatty esters and AcOH/H2O, 9:1, vol/vol for acetylenic fatty esters) to yield the corresponding carboxylic acid moieties in quantitative yields, when the reactions were conducted under ultrasound (20 kHz, 53 W/cm2, 8-15 min). The methyl ester derivatives of the carboxylic acid moieties formed were identified by gas-liquid chromatographic analysis. The procedure constitutes a facile method for the determination of the position of the unsaturated center (olefinic or acetylenic) in an unsaturated fatty ester substrate, especially where the unsaturated system consists of an acetylenic bond.