CLASSIFICATION AND STRUCTURE OF FATTY ACIDS 27 



jugatefl linoleic acids may be pi'oduced by deliydration, which ha\'e con- 

 siderable use in the paint industry. 



The introduction of the hydroxyl group on one of the carbons results 

 in the production of an asymmetric carbon atom. Hence, such acids may 

 frequently be identified and quantitatively determined by their optical rota- 

 tion. Table 4 lists some of the saturated and unsaturated hydroxy- and 

 keto-acids. 



a. Saturated Hydroxy-Acids. The presence of the hydroxyl radical on 

 the fatty acids yields another group in addition to the carboxyl, which 

 may unite with other substances. In the case of sabinic and juniperic 

 acids, the naturally occurring products combine to form an ethoUde in 

 which the properties of alcohols, esters, and acids are combined. They 

 differ from the lactones, in which the union of acid and alcohol groups in- 

 volves only a single molecule. A typical etholide of sabinic acid would 

 ha\'e the structure indicated below. 







HOCHs (GHz ),oC-0-CH2 (CHs ) loCOOH 



Sabinic acid etholide 



Sabinic acid appears only in the savin juniper {Jtmiiperus sabina),^^ 

 while juniperic acid is present in all the conifer waxes which have been 

 examined. The structure of sabinic acid was established by Bougault^^ 

 on the basis of its formation of dodecanedioic acid on oxidation and 

 lauric acid on reduction with zinc and acetic acid. The same investigator 

 also established the structure of juniperic acid. 



No corresponding myristic acids with a hydroxyl on the terminal carbon 

 are known to occur naturally. Ipurolic acid which is present in the seed 

 fat of the Ipomea purpwea (South African morning glory) ^'^ was obtained 

 by Asahina et al.^^'^^ by acid hydrolysis of pharbitic acid isolated from 

 Pharhitis nil Chois. (Japanese morning glory); it had the structure 3,11- 

 dihydroxymyristic acid.^ This was later confirmed.^"" Another mono- 

 hydroxymyristic acid was obtained by Miiller'"^ from Angelica archangelica 

 oil (garden angelica); it is believed to be the 1 1-hydroxy-acid, but the 



3^ J. Bougault and L. Bourdier, /. pharm. chirn. [6], 29, 561-573 (1908-1909); SO, 

 10-16 (1909); Chem. Abst., 3, 2445 (1909). 



'« J. Bougault, Compt. rend., 150, 874-876 (1910). 



9^ F. B. Power and H. Rogerson, Am. J. Pharm., SO, 251-286 (1908). 



88 Y. Asahina and S. X. Terada, J. Pharm. Soc. Japan, No. 452, 821 (1919); Chem. 

 Abst., 14, 310-311 (1920). 



99 y. Asahina and T. Shimidzu, /. Phar7n. Soc. Japan, No. 479, 1-18 (1922); Chem. 

 Abst., 16, 1936 (1922). 



!«>¥. Asahina and S. Nakanishi, /. Pharm. Soc. Japan, No. 520, 515-520 (1925): 

 Chem. Abst., 19, 3479 (1925). 



"» R. Miiller, Ber., 14, 247(5-2484 (1881), 



