CHEMICAL PROPERTIES OF FATTY ACIDS AND RELATED COMPOUNDS 155 



finally the 9,10-linkages.* When the double bonds are conjugated, the 

 addition of the halogens is not complete. For example, 9,10,12,13-octadec- 

 adienoic acid adds only one mole of halogen immediately, while the second 

 mole combines slowly and the reaction is still incomplete after many 

 hours. In the case of a doubly conjugated acid such as elaeostearic acid, 

 halogens add normally to only two of the three unsaturated linkages. 



c. Oxidation of Aliphatic Chains. The unsaturated fatty acids 

 are quite resistant to oxidation, while the unsaturated derivatives are 

 quite susceptible to a variety of oxidizing agents. When they are oxi- 

 dized in the animal body under optimum conditions, or outside the body 

 under a high oxygen pressure in a bomb, the end products are exclusively 

 carbon dioxide and water. However, in the case of less stringent meas- 

 ures, many intermediate products have been reported for the saturated 

 acids. The unsaturated acids are oxidized with considerable ease, forming 

 hydroxy-acids, ketones, and finally breaking down by rupture of the 

 double bonds to shorter chain mono- or di-carboxylic acids. 



(a) Oxidation of Saturated Acids. The saturated acids are not oxidized 

 by air, but they are attacked when treated with oxygen at elevated tem- 

 peratures in the presence of catalysts. When stearic acid is treated in this 

 manner, some of the products identified include shorter chain mono- 

 carboxylic acids, dicarboxylic acids, lactones, lactonic acids, and carbon 

 dioxide. ®^^ Hydroxy-acids have been reported in substantial amounts on 

 oxidation of stearic acid^** or when palmitic acid was treated with hydro- 

 gen peroxide in the presence of cupric salts. ^^* When capric, caprylic, 

 caproic, valeric, and butyric acids were treated with H2O2 in the presence of 

 catalysts, carbon dioxide was found to be an end product. ^^^ Acetic acid, 

 a resistant intermediate product, was also found. 



Oxidation of the saturated acids with concentrated nitric acid leads to the 

 formation of dicarboxylic acids. Myristic acid gives rise to oxalic, suc- 

 cinic, glutaric, pimelic, adipic, and suberic acids.^^^ Dieterle^" reported 

 suberic and sebacic acids from stearic acid, while Carrette®^^ found only 

 succinic and glutaric acids. It would thus seem that the acids which result 

 depend upon the intensity of the oxidation. Potassium permanganate in 

 acetone has been shown to change caproic and heptanoic acids to shorter 



852 A. H. Salway and P. N. Williams, J. Chem. Soc, 121, 1343-1348 (1922). 



65' E. Zemer, Naturprodukte, 1923, 83-94; Chem. AbsL, 18, 112 (1924). 



6" I. Smedley-MacLean and M. S. B. Pearce, Biochem. J., 28, 486-494 (1934). 



655 R. H. Allen and E. J. Witzemann, /. Am. Chem. Soc, 63, 1922-1927 (1941). 



656 H. Noerdlinger, 5er., 19, 1893-1899 (1886). 



657 W. I. Dieterle, Uber die Oxydations-produkte remer Stearinsdure diirch Salpetersdure. 

 II. Beitrag zur Kenntnis der Adipmsdure. Bern, G. F. Rapp, Cannstatt, 1883, 66 pp.; 

 cited by K. S. Markley, Fatly Acids, Interscience, New York. 1947, p. 388. 



658 H. Carrctte, Compt. rend., 102, 692-693 (1886). 



