i6o Plant Pigments [March, 



2 molecules of water. These forms are interchangeable. It is ob- 

 tained free from solvent by precipitation from absolute ether with 

 low-boiling petroleum ether, forming compact needles, melting at 

 159.5-160.5°, depending upon the rate of heating. The ether Solu- 

 tion is orange-yellow ; the alcoholic sol. more red, with a brownish- 

 yellow tinge ; while the carbon di-sulfid sol. is quite red. The pure 

 pigment is stable in an atmosphere of oxygen, but is oxidized in 

 benzene or dilute alcoholic sol., giving a product of approximately 

 the composition, C40H54O16. 



Fucoxanthin does not show acid properties; it is not extracted 

 from ether by aqueous potassium hydroxid sol. and is not changed by 

 50 percent hydroxid sol., solid barium hydroxid or metallic sodium. 

 It reacts with alcoholic potash, forming an addition product. This 

 is decomposed by water but gives, instead of fucoxanthin, a product 

 with increased basic properties and a different absorption spectrum.^'' 

 The ether sol. gives a deep blue salt with dilute hydrochloric acid 

 sol. This behavior may indicate the existence of a pyrone ring in 

 the fucoxanthin. The reaction with alcoholic potash appears to 

 consist in the decomposition of a part of the pyrone nucleus; the 

 hydroxyl group thus f ormed would account for the increase in basic 

 properties.^^ A characteristic of fucoxanthin is its marked basic 

 properties. The other Carotinoids give a deep blue color only with 

 conc. sulfuric acid. Fucoxanthin reacts as a weak base with dilute 

 mineral acids. Thirty percent hydrochloric acid sol. decolorizes the 

 ether sol., itself becoming violet blue in color. With a Solution of 

 the acid in dry ether the hydrochlorid, C4oH5406-4HCl, is ob- 

 tained as blue flakes with a copper luster. When shaken with ether 

 and sodium bicarbonate, a Compound is formed with one atom of 

 chlorin, which gives a greenish yellow Solution. The iodid, 

 C40H54O6I4, forms violet-black, short pointed prisms with a copper 

 luster. 



One k. of fresh algae {Fuchs) contains 0.169 gm. of fucoxan- 

 thin, 0.089 gm. of Carotin, 0.087 g^i. of xanthophyll and 0.503 gm. 

 of Chlorophyll a. 



Rockef eller Institute for 



Medical Research, New York City. 



35 Xanthophyll is stable towards alcoholic potassium hydroxid. 



36 Willstätter and Pummerer: Ber. d. deutsch, ehem. Gesellsch., 37, 3740, 

 1904; 38, 1461, 1905. 



