THE PIGMENTS OF LEAVES 



esters. By the action of methyl alcoholic hydrochloric acid they are changed 

 into methyl esters (methyl phaeophorbides) which are saponified by concentrated 

 hydrochloric acid to the acids (phaeophorbides). The phaeophorbides on heat- 

 ing with alkali are saponified, giving phytochlorin e and phytorhodin g. 

 / COOC 20 H 39 



Phaeophytin a C 32 H M ON 4 <' Phaeophytin b C^H^C^N,^ 



\COOCH 3 \COOCH 8 



Methyl X COOCH 3 Methyl 



phaeophorbide a C 32 H 32 ON 4 N \QQQQj^ phaeophorbide b 



c*f\r\c*ij o/~\/"\oT_T 



s\s\j\j\sn$ s\s\J\J\srl 



Phaeophorbide a C 32 H 30 ON 4 <; Phasophorbide b C 32 H 30 O 2 N 4 <f 



\COOH \COOH 



yCOOH yCOOH 



Phytochlorin e C 32 H 3<) ON 4 >; Phytorhodin g C 32 H 30 O 2 N 4 <f 



\COOH \COOH 



Phytochlorin e and phytorhodin g are the two chief products of the de- 

 composition of the chlorophylls. Their formation led to the discovery of the 

 presence of the two chlorphylls in leaves. The constitution of the molecule 

 of chlorophyll depends upon the constitution of the molecule of aetiophyllin or 

 setioporphyrin. 



The Constitution of Aetiophyllin and Aetioporphyrin. 



The oxidation products of the derivatives of chlorophyll a and chlorophyll b 

 with various oxidising agents are methyl-ethyl-maleinimide and haematinic acid, 

 CH 3 . C CO CH 3 . C CO 



II > H I > NH 



C 2 H 5 . C CO HOOC . CH 2 . CH 2 . C CO, 



the same products which are formed from haemin and its derivatives. 



The derivatives obtained by reducing chlorophyll consist of the three sub- 

 stituted pyrroles (p. 304) : 



Phyllopyrrole 

 Isohaemopyrrole 

 Kryptopyrrole. 



Four pyrrole rings are present in aetioporphyrin united together by two 

 carbon atoms and to one of the pyrrole rings two carbon atoms are attached 

 forming a cyclobutene ring. Willstatter represents the constitution of aetiopor- 

 phyrin and aetiophyllin by the formulae : 



HC=CH HC=CIT 



CHs-c-c. ^c-c 



II ;N N V 



C,H,-C cr 



' n 5 



\\ 



CH 3-0=0 



on-, CH 3 



Aetioporphyrin. Aetiophyllin. 



The COOH groups in the phytochlorin e and phytorhodin g and in the 

 various phyllins are in the positions represented by the ethyl groups as pro- 

 pionic acid radicles. 



The exact constitution has still to be ascertained ; the above are suggested 

 formulae, which may prove to be the correct ones. 



Formulae have not yet been ascribed to xanthophyll, carotin and fuco- 

 xanthin. 



