390 IV. WAXES, HIGHER ALCOHOLS, ETC. 



these saponins are frequently spoken of as triterpene sapogenins. Al- 

 though practically all the triterpenes have been isolated only from plant 

 sources, at least two of them, lanol (lanosterol) and agnol (agnosterol) , 

 which were formerly called isocholesterol, were first isolated from wool fat, 

 where they are associated with the zoosterol cholesterol.-^^ Lanol has also 

 been isolated from yeast, in addition to another sunilar triterpene, cryptol 

 (cryptosterol).^™ The triterpenes have been obtained from all parts of 

 different plants, but only in the sunflower have they been found in more 

 than one part of a single plant. ^'^^ Zimmermann^^' found that, whereas the 

 steryl glycosides or hydrocarbons isolated from fruits and flowers are al- 

 ways the same, the triterpene is related to the type of pigment. Triter- 

 pendiols occur when carotenoid pigments are present, while the triterpene 

 hydroxy-acids are present when the pigments are anthocyanins. 



Noller,^^^ in a comprehensive- revie\y of the triterpenes, has listed the em- 

 pirical formulas and sources of some triterpenes (see Tables 18 and 19). 



In some instances the triterpenes are acids, and in other cases they are 

 alcohols. The relationship between them can be demonstrated by the 

 series of reactions given here, when a carboxyl group is converted to a 

 methyl group: 



-0 /O ,0 



RC-OH ^""'^ . RC-CI "2"' .RC-H-^^^^ RCHj + RCHaOH 



(1) Rosenmund reduction 



(2) Wolff-Kishner reduction 



The interrelation of the various triterpenes is intlicated in Figure 1. 

 There appear to be five groups of triterpenes which have different basic 

 structures. The acyclic group in which squalene is the only member is dis- 



"« H. Wieland, H. Pasedach, and A. Ballauf, Ann., 529, 68-83 (1937). 

 "1 J. Zimmermann, Helv. Chirn. Acta, 26, 642-647 (1943). 

 "2 J. Zimmermann, Helv. Chim. Ada., 27, 332-334 (1944). 

 3" C. R. Nollcr, Ann. Rev. Biochem., U, 383-406 (1945). 

 "^ L. Ruzicka and A. Marxer, Helv. Chim. Acta, 23, 144-152 (1940). 

 3'5 L. Ruzicka and G. Giacomello, Helv. Chim. Acta, 20, 299-309 (1937). 

 "6 L. Ruzicka and G. Giacomello, Helv. Chim. Acta, 19, 1136-1140 (1936). 

 '" L. Ruzicka and H. Schellenberg, Helv. Chim. Ada, 20, 1553-1556 (1937). 

 "8 J. Zimmermann, Helv. Chim. Acta, 19, 247-253 (1936). 

 "9 L. Ruzicka and A. Marxer, Helv. Chim. Ada, 22, 195-201 (1939). 

 38" L. Ruzicka and W. Wirz, Helv. Chim. Acta, 23, 132-135 (1940). 

 3" J. H. Beynon, I. M. Heilbron, and F. S. Spring, /. Chem. Soc, 1937, 989-991. 

 382 P. Bilham, G. A. R. Kon, and W. C. J. Ross, J. Chem. Soc, 1942, 540-544. 

 3" L. Ruzicka, A. Grol), and F. Van der Sluvs-Veer, Helv. Chim. Acta, 22, 788-792 

 (1939). 



38^ D. F. Elliott, G. A. R. Kon, and H. R. Soper, /. Chem. Soc, 1940, 612-617. 

 385 D. Frazier and C. R. Noller, /. Am. Chem. Soc, 66, 1267-1268 (1944). 



