270 III. CHEMISTRY OF NEUTRAL FATS 



metrical) and /3-acyl distearins (symmetrical) were found to have the fol- 

 lowing solubilities expressed in g./lOO ml. in acetone: capryl, 39.45 and 

 2.57 at 29°C.; and palmityl, 1.82 and 0.61 at 27.5°C. Variations of 

 solubility in alcohol are similar, being 0.43 and 0.06 at 23°C. for the acetyl 

 derivatives, 0.22 and 0.14 at 27.5°C. for capryl esters, 0.59 and 0.47 at 

 29°C. for the myristodistearins and 0.42 and 0.10 at 27.5°C. for a-palmito- 

 a',/3-distearin and /3-palmito-Q!,Q;'-distearin, respectively. Even in such 

 an excellent solvent as petroleum ether, a-lauro-Q:',iS-distearin dissolves to 

 the extent of 38.41 g./lOO ml. at 27.5°C., compared with a value of 11.42 g. 

 for )S-lauro-Q:,a'-distearin.^^ On the other hand, the sjonmetrical (13) 

 monoglycerides have been shown to have a somewhat higher solubility 

 than the unsymmetrical (a) members.^"" 



Hixson and Bockelmann^^^ have investigated the solubility of tri- 

 caprylin, tripalmitin, tristearin, and some of the common fats in liquid 

 propane. Data on these tests are summarized in Table 36. 



Table 30 

 Critical Solution Temperature and per Cent Solute per Weight of Fats in 



Liquid Propane" 



Critical solution Per cent solute 



Fat temperature by weight 



Tiicaprylin 100.5° 30.0 



Tripalmitin 73.5° 30.0 



Tristearin 69.2° 28.0 



Cottonseed oil 66 . 3° 29 . 5 



Crisco 70.0° 13.8 



Crude palm oil 71.1° 30.0 



Coconut oil 86.5° 7.0 



Soybean oil 63 . 8° 7.0 



" A. W. Hixson and J. B. Bockelmann, Trans. Am. Inst. Chem. Engrs., 38, 891-930 

 (1942). 



Variations in solubility of the triglycerides occur in acetone at very low 

 temperatures. In general, the triunsaturated triglycerides (GU3) are most 

 soluble, followed by the monosaturated-diunsaturated (GSU2), then by the 

 monounsaturated-disaturated (GSoU) triglycerides. Hilditch'^^ has used 

 this procedure for isolation of the several fractions of natural fats. 



(3) Optical Isomerism 



Since glycerol is capable of asymmetric substitution, many of the 

 glycerides can exist in enantiomorphic forms. This is true of the un- 



3W II. p. Averill, J. N. Roeho, and C. G. King, J. Am. Chem. Soc, 52, 305-367 (1930). 

 '" A. W. Hixson and J. B. Bockelmann, Trans. Am. Inst. Chem. Engrs., 38, 891 930 

 (1942). 



