172 III. CHEMISTRY OF NEUTRAL FATS 



HsCOClCeHslj HzCOClCeHslj HjCOH 



I 2R0C1 ' Hj Pd I 



HCOH ►HCOOCR -^ ►HCOOCR 



HeCOH HzCOOCR HzCOOCR 



l-Tritylglycerol l,2-Diacyl-3- 1,2-Diglyceride 



tritylglycerol 



position occurs under these circumstances. Another workable method 

 used by the same workers is the catalytic reduction of esterified 1-glyceryl- 

 benzyl carbonate. 



(3) Triglycerides 



Chevreul,^^ in 1823, concluded that natural fats are primarily glyceryl 

 esters of palmitic, stearic, and oleic acids, which he believed were present 

 as the simple triglycerides, tripalmitin, tristearin, and triolein. However, 

 Berthelot^'^ first suggested that fats are probably composed to a consider- 

 able extent of mixed triglycerides. This was finally proved to be the case 

 when Fritzweiler^^ and later Klimont^*"^'* isolated several types of mixed 

 triglycerides from various natural fats. However, simple triglycerides, 

 also, can be separated from fats. The synthetic compounds of high purity 

 are readily available. 



a. Simple Triglycerides. Berthelot* demonstrated the production of 

 tristearin by the heating of stearic acid with glycerol over a prolonged 

 period in a sealed tube at 200°C. Garner'*^ developed a method for obtain- 

 ing an almost quantitative yield of pure triglycerides by heating equivalent 

 amounts of glycerol and fatty acids at a temperature of 200 °C. in an at- 

 mosphere of carbon dioxide. Several other procedures have been pro- 

 posed. ^^"^^ These methods are useless for the synthesis of mixed tri- 

 glycerides. 



b. Mixed Triglycerides. As has been noted earlier, it has long been 

 recognized that natural fats contain a large proportion of mixed tri- 

 glycerides. Although a number of these have been separated in pure form 



36 M. E. Chevreul, Recherches chimiques sur les corps gras (1823). Cited by B. F. 

 Daubert and C. G. King, Chem. Revs., 29, 270 (1941). 

 3' M. Berthelot, Ann. chim. phys., 41, 216-319 (1854). 



38 R. Fritzweiler, Arb. kaiserl. Gesimdh., 18, 371-377 (1902); Chem. Zentr., 1902, I, 

 1113. 



39 J. Klimont, Ber., 34, 2636 (1901). 



« J. Klimont, Monatsh., 23, 51-59 (1902). 



41 J. Klimont, Monatsh., 26, 563-569 (1905). 



« J. Klimont, Z. Untersuch. Nahr. u. Genussm., 12, 359-360 (1906). 



43 J. Klimont, Monatsh., 25, 929-932 (1904). 



44 J. Klimont and E. Meisels, Monatsh., 30, 341-346 (1909). 



45 T. L. Garner, /. Soc. Chem. Iml, 47, 278-280 (1928). 



46 E. B. Herschberg, /. Am. Chem. Soc, 61, 3587-3588 (1939). 



47 R. K. Newman, J. M. Trikojus, and G. Marker, Proc. Roy. Soc. N. S. Wales, 59, 

 293-300 (1926). 



48 P. E. Verkade, J. van der Lee, and W. Meerburg, Rec. trav. chim., 51, 850-852 

 (1932). 



