20 II. CHEMISTRY OF FATTY ACIDS AND GLYCEROL 



from marine oils have been prepared, namely clupanodonic acid, which has 

 5 double bonds, and nisinic acid, a hexaethenoid acid from Japanese sardine 

 oil {Clwpanodon melanostica) . The term, clupanodonic acid, was first 

 applied by Tsujimoto^^ to a C18H28O2 acid; he later concluded that it 

 should be assigned to the C22H34O2 compound.^- Toyama and Tsuchiya*^ 

 gave the name morodic acid to the Cis acid. The data on these acids are 

 given in Table 3. 



a. Linoleic Acid. From a quantitative standpoint, linoleic acid is 

 the most important of the polyethenoid acids found in vegetable oils. 

 In a number of the less common vegetable oils, this acid may comprise 

 as high as 70 to 80% of the total fatty acid (grapeseed, hackberry tree 

 acid, tobaccoseed, Thom apple, and walnut), while many of the common 

 food oils may have 50% or more of this acid (hempseed, poppyseed, saf- 

 flowerseed, sunflowerseed, cottonseed, and soybean oils). Contrasted with 

 these values, the amount which occurs in animal fats is quite low unless 

 diets containing liberal amounts of linoleic acid are ingested (see Table 22, 

 Chapter III). 



According to Boswoi'th and Brown, -^ linoleic acid is probably absent 

 from butter fat. Neither linoleic acid nor any other diethenoid acid is 

 normally found in the fat of marine animals. The absence of large 

 amounts of this acid in animal fats is apparently related to the inability of 

 the animal cells to synthesize acids with more than one unsaturated link- 

 age or, at least, to form it at a rate demanded by the growing organism.^' 



The generally accepted foimula for linoleic acid, 9,12-octadecadienoic 

 acid, has been arrived at by a study of its oxidation products. Tetra- 

 hydroxystearic acid is first formed, but this breaks down to cleavage prod- 

 ucts. ^^"''^ The suggestion that this acid is 9,14-octadecadienoic acid^^ 

 has been adequately refuted by Arcus and Smedley-MacLean,^* who used 

 an ozonolysis technic similar to that of the Japanese investigator, and still 

 obtained results in accord with the generally accepted structure. 



Since linoleic acid has two ethylenic bonds, there are four possible 



31 M. Tsujiinoto, J. Coll. Eng. Tokyo Imp. Univ., 4, No. 1 (1906); cited by A. W. 

 Ralston, Fatty Acids and Their Derivatives, \^'iley, New York, 1948, p. 143. 



32 M. Tsujimoto, J. Soc. Chem. Ind. Japan, h, 1007-1010 (1920); Chem. Abst., 15. 

 1227 (1921). 



33 Y. Toyama and T. Tsuchiya, Bull Chem. Soc. Japan, 10, 232-241 (1935). 

 3* H. H. Williams and W. E. Anderson, 0/7 & Soap, 12, 42-44 (1935). 



•« G. L. Goldsobel, J. Russ. Phys. Chem. Soc, 38, 900-901 (1906); futed by A. W. 

 Ralston, Fatty Acids and Their Derivatives, Wiley, New York, 1948, p. 126. 



3« T. Maruyama, J. Chem. Soc. Japan, 5J,, 1073-1081 (1933); Chem. Abst., 28, 1015 

 (1934). 



3' L. C. A. Nunn and I. Smedley-MacLean, Biochem. J., 29, 2742-2745 (1935). 



3»K. Takahashi, J. Chem. Soc. Japan, 42, 130-141 (1921); Abst. Chem. Papers, 

 120, Part I, 303 (1921); Chem. Abst., 15, 2273-2274 (1921). Cited by C. L. Arcus and 

 I. Smedley-MacLean, Biochem. J., 37, 1-6 (1943). 



39 C. L. .\i-cus and I. Smedlev-MacLttui, Biochrm. J., 37, 1-6 (1943). 



