Stearic acid, methyl ester, transesterification

Parrish (1977) reviewed the research and development of lactose ester-type surfactants carried out by Scholnick and his colleagues (Scholnick et al. 1974, 1975 Scholnick and Linfield 1977). Their initial attempts to form lactose esters followed the same transesterification procedures that had been used with sucrose (a fatty acid methyl ester in N,N-dimethylformamide with potassium carbonate as the catalyst). Their successful approach was the reaction of lactose in N-methyl-2-pyrrolidone as the solvent with fatty acid chlorides, resulting in yields of 88 to 95% for esters of lauric, myristic, palmitic, stearic, oleic, and tallow fatty acids. The principal product was the monoester, which is important for detergent use, since diesters and higher esters of lactose are not water soluble. 

In soybean lecithin, the acyl groups consist of oleic, linoleic, linolenic, stearic, and palmitic acids. Hydrogenated lecithin contains only stearic and palmitic acid groups. Lecithin can be characterized in terms of its total fatty acid composition. Total fatty acid composition is determined by saponification of the ester and esterification of the isolated acids with BF3 in methanol, followed by gas chromatography of the fatty acid methyl esters (33). There is evidence that methanolic sodium methoxide gives the best yields in transesterification (34). 

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