102 



II. DIGESTION AND ABSORPTION' OF FATS 



coordination numbers of choleic acids composed of mono- or dicarboxylic 

 acids are illustrated in Figure 1 . 



In the fatty acid series, formic acid alone fails to yield a choleic acid, 

 and acetic acid gives the only product having a single bile acid molecule. 

 The normal coordination number for propionic and butyric acids appears 

 to be 2, although choleic acids containing 3 and 4 units, respectively, have 



fl- 1 2 3 7 8 



Fig. 1. Coordination numbers of choleic acids containing mono- or dicarboxylic 

 acids. 526 The abscissae represent the number of methylene groups present in each 

 acid, while the ordinates indicate the number of molecules of desoxycholic acid 

 which combine with a single molecule of each respective acid. 



likewise been reported. 527 All straight-chain acids from C 5 to C 8 have 

 coordination number 4, while acids from C 9 to d 4 combine with 6 desoxy- 

 cholic acid molecules. For the remaining acids of the n-series, the coordina- 

 tion number is 8 (up to C27). In the branched-chain acids, the coordina- 

 tion numbers are ordinarily those of the longest straight chain in the 

 molecule. 526 The branched chain may interfere with choleic acid forma- 

 tion, 52 * as is indicated by the fact that hexamethylethane forms no ad- 

 dition compound in alcohol. 529 



526 H. Sobotka and A. Goldberg, Biochem. J., 26, 555-568 (1932). 



527 The designation "monocholeic, dicholeic, tetracholeic" acids, etc., is sometimes 

 applied to choleic acids containing 1, 2, or 4 molecules of desoxycholic acid, respectively, 

 to one molecule of the acholic component. 



528 E. Chargaff and G. Abel, Biochem. ./., 28, 1901-1906 (1934). 



529 L. F. Fieser and M. S. Newman, ./. .1///. Chem. Soc, 57, 1602-1604 (1935). 



