Semiquantitative structural analysis of fats by thin‐layer chromatography of the allyl esters of the products of von rudolff oxidation

Each unsaturated acyl group in a fat molecule retards its migration on a silica‐silver nitrate TLC plate to a degree dependent on its number of double bonds. Thus S 2 U in which U is linoleic would migrate with SU 2 in which U is oleic. Therefore the molecular families S 3 , S 2 U, SU 2 and U 3 cannot be separated, as such, by this variety of TLC. Oxidation of fats by the von Rudloff technique converts the glyceryl esters of the original unsaturated acids into the glyceryl half esters of dicarboxylic saturated acids, such as azelaic. Subsequent formation of allyl esters at the free carboxyls, in effect replaces each mono‐ or polyunsaturated acyl group with another group containing only a single double bond. Fats so altered can be separated, at least semiquantitatively, into the famlies S 3 , S 2 U, SU 2 , and U 3 where U is monounsaturated and represents, but is not identical with, the original acyl group. These results can be translated directly into the percentages of the original molecular families. Results of determinations are given. Procedures for assigning spots to specific molecular families are (1) comparison of R f ȕ 100 values with given experimental ranges, (2) comparison of the percent of S theoretically present after tentative assignment of spots, with the percent of S found by GLC analysis of the sample, (3) use of internal standards, and (4) miscellaneous.