CHLOROPHYLL 319 



The two isochlorophyllins a and h heated with alkali go 

 through a similar series of changes yielding dicarboxylic acids 

 cyano-, erythro-, and rubi-phyllin, and finally both yield the 

 same monocarboxylic acid, phyllophyllin C3iH33N4MgCOOH. 



The Action of Acids. 



Acids, especially oxalic acid, remove magnesium from all 

 derivatives containing this element, replacing it by two atoms 

 of hydrogen without altering the rest of the molecule. 



Thus chlorophyll a and h give by removal of Mg the com- 

 pounds — 



/COOCH3 

 Phaeophytin a C32H320N4^ and 



\COOC20H3,, 



/COOCH3 

 Phaeophytin b C3oH3q02N4<^ 



\COOC20H39 



respectively, while chlorophyllin a gives phytochlorin / and 

 g, C32H320N4(COOH)2. On the otherh and, glauco- and 

 rhodophyllin by removal of magnesium give glauco- and 

 rhodoporphyrin C3iH34N4(COOH)2, while pyrrophyllin yields 

 pyrroporphyrin C3iH35N4(COOH). By removing the last car- 

 boxyl from the latter compound a substance aetioporphyrin 

 C31H36N4 is obtained, which is the magnesium free analogue 

 of aetiophyllin C3iH34N4Mg — 



CH=CH 



CH., C— CH, 



> K II 



C2H5 C C^ C CH 



C^H, C=C ^C— C . C2H5 



^NH HN<^ 



CHg C C C C . CH3 



CIi3 Cri3 



Aetioporphyrin, C31H36N4 



CRYSTALLINE AND AMORPHOUS CHLOROPHYLL. 



From the data in the table given on page 316, it will be 

 seen that neither ordinary chlorophyll {a and b) nor either of 

 the constituents of this mixture show any marked tendency 



