CAROTENOLS AN'D OXYCAROTENOLS OF THE C40 SERIES 577 



occurs in the esterified form. The presence of this carotenoid is not limited 

 to the phmt kingdom, as is indicated by the fact that it has been isolated 

 from human fat.'^^ 



c. Related Compounds, (a) Perhydrocapsanthin, CioHisOs. When cap- 

 santhin is reduced with platinum, the pigment absorbs ten molecules 

 of hydrogen, and changes to a thick, colorless oil. This product is more 

 soluble in organic solvents than is the parent carotenoid. The carbonyl 

 group is retained in perhydrocapsanthin ; however, if this compound is 

 further treated with sodium and alcohol, the carbonyl group is reduced, and 

 the completely hydrogenated triol, C40H80O3, results. ^'^^ 



(6) Capsatithol, C40H60O3. Wlien capsanthin is reduced with aluminum 

 isopropoxide in isopropanol, capsanthol is foiTned.^^^ It can be purified 

 through adsorption on calcium hydroxide from a benzene solution. WTien 

 crystallized from ethanol, it forms brown-red leaflets which appear yellow 

 under the microscope. It melts at 175-176°C. It is difficultly soluble in 

 boiling alcohol. 



Capsanthol 



(c) Capsanthin Diesters. Capsanthin diacetate, C44H62O6, is prepared 

 by treating capsanthin in pyridine solution with acetyl chloride. ^^^ It can 

 be purified chromatographically on calcium hydroxide; it ciystallizes from 

 methanol in platelets which melt at 146. 5°C. It is very soluble in chloro- 

 form, diethyl ether, carbon disulfide, and benzene, and somewhat less so in 

 methanol. "V^Tien it is partitioned between methanol and petroleum 

 ether, the ester passes quantitatively into the upper layer (petroleum 

 ether). The following diesters are synthesized by an analogous proce- 

 dure : 



Cap.santhin dipropionate, C46H66O0 (m.p., 140°C.). 



Capsanthin dicaprate, C60H94O5 (violet-stippled red plates melting at 109°C.)^'''" 



Capsanthin dimyristate, CbsHhoOs (red needles melting at 88°C.). 



Capsanthin dipalmitate, C72H118O5 (Bordeaux red crystals melting at 95°C.).2^*'"* 



Capsanthin distearate, CreHvieOs (m.p., 84°C.). 



Capsanthin dibenzoate, C54H66O5 (m.p., 121-122°C.). 



(d) Capsanthinone, C40H58O5. When capsanthin diacetate is oxidized 

 with chromic acid, the triketone capsanthinone results. ^^^ Capsanthinone 

 diacetate crystallizes from a benzene-hexane mixture in needles having a 



'"' P. Karrer and H. Hiibner, Helv. Chim. Acta, 19, 474-479 (1936). 

 3'< L. Zechmeister and L. v. Cholnoky, Ann., 543, 248-257 (1940). 



