Preparation of malvalic and sterculic acid methyl esters from Bombax munguba and Sterculia foetida seed oils

A method has been developed for the preparation of highly pure malvalic (ci s-8,9-methyleneheptadec-8-enoic) and sterculic (cis-9,10-methyleneoctadec-9 -enoic) acid methyl esters starting from Bombax munguba and Sterculia foeti da seed oils. The methyl esters of these oils were prepared by sodium methy late-catalyzed transmethylation followed by cooling (6 degrees C) the hexan e solution of crude methyl esters and separation of insoluble fatty acid me thyl esters by centrifugation in the case of B. munguba and by column chrom atography in the case of S. foetida. Subsequently, the saturated straight-c hain fatty acid methyl esters were almost quantitatively removed by urea ad duct formation. Finally, methyl malvalate and methyl sterculate were separa ted from the remaining unsaturated fatty acid methyl esters, in particular methyl oleate and methyl linoleate, by preparative high-performance liquid chromatography on C-18 reversed-phase using acetonitrile isocratically. Met hyl malvalate and methyl sterculate were obtained with purities of 95-97 an d 95-98%, respectively.