1814 



SPECTROSCOPY AND FLUORESCENCE OF PIGMENTS CHAP. 37C 



The OH group re-appears in fraction No. 2 in pyridine. This is re- 

 markable since, with the bond between Cg and Cio assumed to be broken 



90 



eo 



70 

 60 

 50 

 40 

 30 

 KX) 

 S90 



|eo 



t70 



«60 



2 50 



-40 



-90 



BO 



70 



60 



50 



40 



30 



20 



10 



jm 



PYRIDINE VS PYRIDINE 



'° \ /I /pyridine 



O-HP 



36 32 28 24 20 19 18 



16 15 14 13 12 



rREOUENCY'CM"lx lO'^ 



(a) 



17 « 15 

 frequfncy;Cm"'xio"' 



(b) 



Fig. 37C.15. Infrared absorption spectra of allomerized ethyl chlorophyllide a. 

 (a) Intact chlorophyllide, and three fractions of its allomerization product, all in CHClj. 

 Note differences in the C=0 band region (1600-1800 cm.-i). (6) Main allomerization 

 product ("fraction No. 2") in CHCU, CCI4 and C5H5N (after Holt and Jacobs 1954). 

 Note evidence of a lactone structure in CCI4 (and probably also in CHCI3), and of an 

 OH group in pyridine. 



in the allomerized state, where can the H-atom needed for enolization 

 come from? Shall perhaps this result be taken as an argument for re- 



