564 VI. CAROTENOIDS AND RELATED COMPOUNDS 



cyclohexane, acetic acid, and acetic anhydride, but only when these solvents 

 are hot. Physalien is almost completely insoluble in ethanol and acetone. 

 When dissolved in concentrated sulfuric acid, it develops a deep blue color. 



HjC CHj H,C CHj 



C CHj CHj CHj CHj q 



/\ hhIhhhIhhhhIhhhIhh /\ 

 HjC c-c:C'C:C'C.'C'C:C'C:c-C:C-C:C-c:c-c:c-c ch? 



H\l il li l/H 



c C C C 



CHy{CHs)uC-0^ ^/ \^^ ^^/ ^^^ ^0-C(CHj),4CH, 



H2 ^ ' H? 



Physalien (zeaxanthin dipalmitate) 



In addition to the synthesis of physalien, a number of the di-esters and 

 some mono-esters have been prepared by Karrer and several collaborators. 

 The synthesis was accomplished by mixing the free zeaxanthin in pyridine 

 with the appropriate acid anhydride or acid chloride; this was employed 

 earlier by Karrer and Ishikawa^^^ for the preparation of the lutein esters. 

 The following zeaxanthin esters have been synthesized and characterized: 

 zeaxanthin diacetate, C44H60O4 (m.p., 154-155°C.)'^^; dipropionate, 

 C46H64O4 (m.p., 142°C.)io^ dibutyrate, C48H68O4 (m.p., 132°C.)io4; di-n- 

 valerate, C50H72O4 (m.p., 125°C.)^''*; di-n-caproate, C52H76O4 (m.p., 117- 

 118°C.)io*; di-n-caprylate, C56H84O4 (m.p., 107°C.)i'"'; dilaurate, C64Hioo04 

 (m.p., 104°C.)2^3. and distearate, C76H124O4 (m.p., 95°C.)25 The monopal- 

 mitic ester of zeaxanthin (C56H86O4) was prepared by partial saponification 

 of physalien. ^^- When ciystallized from a benzene-ethanol mixture, it 

 forms platelets which melt at 148°C. In addition to the several esters, 

 zeaxanthin forms mono- and di-ethers. Dimethyl zeaxanthin ether (C40- 

 1164(00113)2) has been prepared^^^ as a crystalline product which melts at 

 175-176°C. 



(6) Physalienone, C72H116O8. When physalien is oxidized with chromic 

 acid,^^* a tetraketone is formed which was found to have the structure'^'* 

 given below. Physalienone forms fine, bushy needles. The melting point 

 is 144-145°C. 



H)C CH3 HjC CH3 



CH3 CHj CHj CH; 



/ " \ /"h hIhhhIhhhhIhhhIh h".^ /~\ 



HzC c-c: C- c: C • c: C' c: C • c: C- C; C- C: • C: C- c: c-c CHs 



Q C C=0 0=0 C o 



CH,(CH,).,CO^ \/ \^^^ H.C^ ^0^ ^OC(CH,UCH, 



Hj Hj 



Physalienone 



(c) Zeaxanthin Mono-epoxide, Anther axanthin, C40H56O3. When zeaxan- 

 thin is oxidized with perphthalic acid, two oxidation products result, 



332 P. Karrer and U. Solmssen, Helv. Chini. Ada, 18, 477-480 (1935). 



333 p. Karrer and T. Takaha,sh[,.Helv. Chim. Acta, 16, 1163-1165 (1933). 

 33* P. Karrer and W. Gugelmann, Hclv. Chim. Ada, 20, 405-406 (1937). 



