COMPOSITION OF NATUKAL FATS AND OILS 211 



Mououiisaturatcd disaturated triglyceride (II) 



HaCOOC (CHslieCHj HzCOOClCHzJieCHj 



HCOOC{CH2),6CH3 HC00C(CH2)7CH.CH(CH2)7CH5 



H2COOC{CH2)7CH:CH(CH2)7CH5 HjCOOClCHzl.sCHj 



a-Oleo-a, '/3-distearin /3-01eo-a,a'-distearin 



Monosaturated di unsaturated triglycerides (III) 



HjCOOClCHzlisCHs H2C00C(CH2)7CH:CH (CH2)7CH3 



HCOOC(CH2)7CH:CH(CH2)7CH3 HCOOC(CH2),6CH3 



H2COOC(CH2)7CH:CH(CH2)7CH5 HjCOOC(CH2)7 CH-CH(CH2)7 CHj 



a-Stearo-a', /3-diolein /3-Stearo-a,a'-diolein 



Triunsatui'ated glyceride (IV) 



H2COOC(CH2)7CH:CH(CH2)7CH3 

 HC00C(CH2)7CH:CH{CH2)7CHj 

 H2C00C(CH2)7CH:CH(CH2)7CH3 



Triolein 



Hilditcli and his associates have been able to classify the fats into the four 

 general groups, i.e., trisaturated or fully saturated, monounsaturated- 

 disaturated, monosaturated-diunsaturated, and triunsaturated. It is not 

 possible, by the routine procedures developed by Hilditch, to differentiate 

 between the symmetrical and the unsymmetrical mixed triglycerides; spe- 

 cial methods must be employed to determine the proportion of their isomers, 

 and estimates have been made in only a few cases. 



The most satisfactory terminology for describing the several classes of 

 triglycerides is probably that employed by HilditchJ' 



Group I. Trisaturated, C3H5(0 • CO • 8)3 or GS3. 



.(0- CO -8)2 

 Group II. Monounsaturated-disaturated, C^f/C or GS2U. 



\0-CO-U) 



/(0-CO-S) 

 Group III. Monosaturated-diunsatui'ated, CsHj^ or GSU2. 



\0-C0-U)2 



Group IV. Triunsaturated, C3H5(0 • CO -U)., or GU3. 



(a) Determination of Fully Saturated Glycerides (Hilditch). The method 

 of Hilditch and Lea-'® offers an especially satisfactory and accurate system 

 for the determination of GS3 in the presence of GS2U, GSU2, and GU3. 

 This procedure is based upon the earlier observation of Armstrong and 

 Hilditch-*'^ that the saturated triglycerides possess extreme stability to- 

 ward oxidation, in contrast to the ready susceptibility of the triglycerides 



^o T. P. Hilditch and C. H. Lea, J. Chem. Soc, 1927, 3106-3117. 



25' E. F. Armstrong and T. P. Hilditch, /. Soc. Chem. Ind., 44, 180-189T (1925). 



