PROPERTIES OF THE CAROTEXOIDS 



60- 



The absorption maxima and, in fact, the shape of the absorption curve, 

 are to a great extent related to the molecular structure. The greater the 

 number of conjugated double bonds which occur in an miinterrupted series, 

 the longer are the wave lengths at which absorption will obtain, and the 

 higher on the scale the color which will be exhibited by solutions of such 

 carotenoids. Where the pattern of conjugated double bonds is identical 

 for several compounds as, for example, is the case with jS-carotene, ciypto- 

 xanthin, and zeaxanthin, the absorption spectra would be expected to be 



Plate 1. Spectrograms of carotene and xanthophyll according to Will- 

 statter and StolP*": (1) carotene in alcohol; (2) xanthophyll in alcohol; 

 (3) carotene in carbon disulfide; (4) xanthophyll in carbon disulfide.^' 



similar. This hypothesis finds support in the well-known fact that it is 

 practically impossible to differentiate among the above three carotenoids 

 solely on the basis of their spectrometric beha\nor. 



When an alteration in the chromophore system occurs, a marked change 

 in the absorption spectrum always results. On the other hand, a very con- 

 siderable change in the structure of the molecule can be brought about 

 without any change in the absorption properties, provided that the chromo- 



