236 Willstättcr's Rescarches on Chlorophyll [Jan. 



crystallizing, its ether Solution does not give the brown phase when 

 shaken witli alcoholic potash sol., and it does not yield the normal 

 decomposition products but more vveakly basic ones. It is thoiight 

 that the change consists in the opening of the lactam grotip and the 

 formation of a new lactam group (see page 243). If a different 

 amino group or carboxyl group is involved in this reaction it is clear 

 that an isomeric Chlorophyll of different basic or acidic character 

 will be formed. Allomerization does not take place in ether, Chlo- 

 roform or water-free pyridine. It appears to be catalysed by glass, 

 since an alcoholic sol. in a platinum or silver vessel shows very 

 little change. While it does not appear that the alkali of the glass 

 is responsible for the change, yet it is completely prevented by the 

 presence of small amounts of acid, o.oi gram of oxalic acid in i 

 liter of alcohol being sufficient. This accounts for the presence of 

 oxalic acid in the alcohol used for the Separation of the two Chlo- 

 rophyll components. 



The Chemical properties of Chlorophyll. The parent substance 

 of Chlorophyll is a tricarboxylic acid, called chlorophylline, 

 C3iHo9N4Mg(C02H);{. In Chlorophyll one carboxyl group is 

 esterified with methyl alcohol, a second with the unsaturated alco- 

 hol, phytol, C20H40O, while the third is probably present as the 

 lactam group. Thus we may represent Chlorophyll, or methyl phy- 

 tyl chlorophylline, in the following manner : 



C20H39COO NH— CO 



MgNgCgiH^aCOOCH, 



When treated with the enzyme, the phytol group is split off, giving 

 chlor ophyllide, or methyl chlorophylline, which loses its methyl alco- 

 hol group under the influence of hot or cold alkali sol., giving chlo- 

 rophylline : 



C20H39COO NH^CO COOK NH— CO 



MgNsCsiHsgCOOCHg MgNaCaiHooCOOCHg 



COOK NH— CO 



MgN3C3,H2,COOH 



Chlorophyll — > Chlorophyllide — > Chlorophylline 



