- 79 - 



The principal allomerization products of a and b did not yield 

 additional pigments (isomerization products), separable by chromatog- 

 raphy, -when n-propanol solutions were heated to 100" for an hour ' ^o 



Formatio n of Pheophytins 



When plants that contain strongly acidic juices are killed in 

 various ways or extracted with methanol, the acids convert the chloro- 

 phylls into the weakly adsorbed, magnesium-free pheophytinSo This 

 deleterious effect may be reduced by rapid extraction and also by the 

 addition of dimethylaniline to the extraction solvent. 



With the extracts of acidic leaves adsorbed in columns of sugar, 

 the pheophytin a formed a gray zone below chlorophyll _a' , Pheophytin 

 b formed a yellow-gray zone below the lutein zone and well above chlo- 

 rophyll a. 



THhen solutions of the pheophytins in n-propanol were heated, the 

 a and the b pheophytins yielded less sorbed pigments that were recon- 

 vertible to the a and the b pheophytins , These less sorbed pheophytins 

 correspond to the chlorophyll isomers a' and b' s 



Chlorophyll d treated with acid at low temperature yielded 

 pheophytin d that formed a yellow zone in the sugar columns o Vfith 

 acid at room temperature, the d yielded isopheophytin d that formed 

 a gray zone in the columnso With heat or upon standing, pheophytin d_ 

 yielded a similar less sorbed pigment, pheophytin d' , corresponding to 

 chlorophyll d' , and isopheophytin d yielded a less sorbed isomer, iso- 

 pheophytin d, corresponding to isochlorophyll d' „ The relative posi- 

 tions of the principal pheophytins in a sugar column washed with 

 petroleum ether containing Ool per cent n-propanol are shown by Fig- 

 ure 111,17, 



