SYNTHESIS OF THE GLYOERIDES 177 



with many hydrogenated fats produced in the United States. The main 

 chemical difference between the synthetic fats from petroleum and the 

 natural fats and those hydrogenated from vegetable oils is that the former 

 contain approximately 50% odd-chain fatty acids while, of course, all 

 natural fats consist solely of even-chain fatty acids. Moreover, consider- 

 able amounts of branched-chain acids have also been reported in the syn- 

 thetic fats; 2-, 3-, and 4-methylated acids have been detected, and it is 

 probable that the ethyl-branched chain acids occur in small amounts. 

 Dicarboxylic acids from Cio to C14 are likewise present^^-^^ to the extent of 3 

 to 4% of the crude fatty acid mixture obtained by oxidation of petroleum 

 products, but they are almost completely eliminated from the refined fat. 

 Other compounds present in small amounts include hydroxy- and keto- 

 acids, lactones, as well as aliphatic alcohols and ketones.®^ Finally, the 

 synthetic fat contains practically no unsaturated acids. 



Thomas and WeitzeP^ have suggested that the reactions involved in the 

 formation of fatty acids from paraffins require several steps. The primary 

 reaction results in an unsaturation at the middle of the molecule of the 

 carbon-to-carbon linkage. This is followed either by an oxidative splitting 

 of the olefin so produced to the acids , or by the intermediate formation of a 

 peroxide.™ A schematic example of this process as suggested by WeitzeF^ 

 follows: 



CH5(CHj)xCH2CHj(CH2),CH3- 

 Hydrocarbon 



CH3(CH2)xCOOH+HOOC(CH2),CH3 



Fatty Fatty 



acid acid 



Since the maximum desirable length of the fatty acids for soaps or for food 

 fats is 18 carbons, the hydrocarbons should not exceed 35 carbons in length. 

 The assumption that oxidation occurs on the tertiary carbon atoms of the 

 paraffin at the site of the branched chain^®-^' is apparently incorrect, since 

 considerable amounts of iso-acids have been demonstrated.^^ 

 The question of toxicity of the synthetic fats is not as yet completely 



67 W. Keil, Z. physiol. Chem., 274, 175-185 (1942). 



«8 H. Appel, H. Bohm, W. Keil, and G. Schiller, Z. physiol. Chem., 282, 220-244 

 (1947). 



69 K. Thomas and G. Weitzel, in R. Kuhn, Fiat Rev. German Sci., Biochemistry, 1, 

 1-58 (1947). 



'» A. Imhausen, Kolloid-Z., 103, 105-108 (1943). 



" G. Weitzel, Fette u. Seifen, 46, 21 (1939). Cited by K. Thomas and G. Weitzel in 

 R. Kuhn, Fiat Rev. German Sci., Biochemistry, 1, 30 (1947). 



" G. Weitzel, Angew. Chem., 51, 531-546 (1938). Cited by K. Thomas and G. 

 Weitzel, in Fiat Rev. German Sci., Biochemistry, 1, 30 (1947). 



