PIGMENTS 



105 



/COO-CHs 

 R/ 



XJOO- C 2 oH 39 



Amorphous chlorophyll 



or 



methyl-phytyl chloro- 

 phyllide 



/COO-CHs 

 \COO- C 2 H 5 



Crystalline chlorophyll 



or 



methyl-ethyl chlorophyl- 

 lide 



CH 

 H 



Chlorophyllin 



" Chlorophyllin," the compound in which the ester groups 

 have been converted into free acid groups, as indicated above, 

 may be obtained from either amorphous or crystalline chlorophyll 

 by treatment with caustic potash dissolved in methyl alcohol. 



Phytol. This alcohol, which furnishes the characteristic ester 

 group in the chlorophyll of plants, is a compound of very unusual 

 composition, which has never been found in any other form or in 

 any other type of compound which is present in either plant or 

 animal tissues. Careful studies of its addition and oxidation 

 products prove that it has the following structural arrangement: 



HHHHHHHH H 



H-C-C C C C C C C ' H ' 

 H CH 3 CH 3 CH 3 CH 3 CH 3 CH 3 CH 3 CH 3 CH 3 CH 3 



As this formula indicates, the compound contains one unsaturated, 

 double-bond linkage, one primary alcohol group, and eleven 

 methyl groups. As has been said, this alcohol occurs nowhere 

 else in nature, and its presence and function in the chlorophyll 

 molecule are, as yet, wholly unexplainable. Phytol itself is a 

 colorless, oily liquid, with a high boiling point (145 in vacuo, 

 204 at 10 mm. pressure). 



THE CONSTITUTION OF THE CHLOROPHYLLS 



As has been mentioned, chlorophyll a differs from chlorophyll b 

 by having one more oxygen and two less hydrogen atoms in the 

 molecule, and in having one of its nitrogen atoms in the " lactam " 

 arrangement. These differences in structure are represented by 

 the following formulas which are commonly used to represent the 

 two compounds, but which do not show the arrangements of the 

 major groups of the complex molecules: 



