70 II. CHEMISTRY OF FATTY ACIDS AND GLYCEROL 



later by the American Oil Chemists' Society.--^ A slightly different method 

 is recommended by Hilditch' for larger quantities of solid acids. 



However, neither the lead-salt-ether method nor the lead-salt-alcohol 

 procedure gives an exact separation of saturated and unsaturated acids. 

 Jamieson^^" states that the results are particularly unsatisfactory^ Avhen used 

 with butter fat, coconut, palm kernel, or similar oils in which saturated 

 fatty acids such as myristic (Ch) or those with shorter chains are present 

 in an appreciable amount. The lead salts of such short-chain fatty acids 

 are quite soluble in ether or in alcohol, and would thereby be confused with 

 the unsaturated acid fraction. Difficulties are also encountered with 

 rapeseed or mustardseed oils because of the poor solubility of the lead 

 salt of emcic acid, and its subsequent inclusion in the saturated fatty acid 

 fraction. Similar difficulties are encountered with fats containing appre- 

 ciable amounts of elaeostearic acids, such as China wood (tung) oil {Aleu- 

 riles Jordi) or hydnocarpic or chaulmoogric acids, which are present in 

 chaulmoogra oil. Finally, the lead salts of some of the solid iso-oleic acids, 

 formed during the hydrogenation of fats, are likeAvise largely insoluble, 

 so that the Twitchell method must be modified when applied to hydro- 

 genated fats. When such limitations of the lead-salt method are realized, 

 they can be corrected by certain modifications. 



(6) Barium Salts in Benzene. A somewhat less satisfactory procedure 

 for the separation of the saturated from the unsaturated acids depends 

 upon the difference in the solubility of the barium salts in benzene. -^^ 

 The barium-salt procedure ^"^ has been employed also for the concentration 

 and isolation of hydroxypalmitic acid from butter fat, as well as for the 

 preparation of oleic acid of high purity from refined and commercial olive 

 Qjjg232,233 ^^f[ fQj. iJ^Q separation of oleic and linoleic acids from linseed 

 oil. 2*^ Smith and ChibnalP^^ used as a solvent benzene containing 5% of 

 95% ethanol for separating the fatty acids of forage grasses as their barium 

 soaps. 



(c) Lithium Salts in Acetone. Another useful procedure for the further 

 fractionation of the unsaturated acids was introduced by Tsujimoto.^-''^^-^" 

 This author showed that the lithium soaps of tetraethenoid and penta- 

 ethenoid acids are soluble in 95% acetone while those of the less highly un- 

 saturated acids are much less soluble in this solvent. The procedure has 



230 G. S. Jamieson, J. Assoc. Official Agr. Chem., 11, 301-310 (1928); Vegetable Fats 

 and Oils, 2iid ed., Reinhold, New York, 1943, i). 407. 



"IK. Farnsteiner, Z. Untersuch. Nahr. Getiussm., 2, 1-27 (1899); 4, 63-65 (1901); 

 6, 161-166 (1903). 



"2 A. Lapworth, L. K. Pearson, and E. N. IMottrani, Biochem. ./., 19, 7-18 (1925), 



2" J. H. Skellon, J. Soc. Chem. Ind., 50, 131-134T (1931). 



"^ E. Erdmann and F. Bedford, Ber., J,2, 1324-1333 (1909). 



23* J. A. B. Smith and A. C. Chibnall, Biochem. J., 26, 218-234 (1932). 



236 M. Tsujimoto, Chem. Umsrhau, 33, 285-291 (1926); Chem. Abst., 21, 661 (1927). 



287 M. Tsujimoto and K. Ivimui-a, J. Soc. Chem. lad. Japan, 26, 891-893 (1923); 

 Chem. Abst., 18, 2259 (1924). 



