244 IVillstätter's Researches on Chlorophyll [Jan. 



The allomerized product probably has the same strticture as the 

 product obtained by the action of alkah in the cold, i. e., the original 

 lactani gronp may be opened by the continued action of alcohol or 

 petroleum ether; and since the new group is not reactive, the reac- 

 tion proceeds to completion in the direction of the allomerized 

 product. It is also possible that the original lactam group may be 

 opened in alkaline sol. and then reformed again. This possibility 

 is found in the " brown-phase " test. If an ethereal sol. of Chloro- 

 phyll is shaken with methyl alcoholic potash sol., the Chlorophyll 

 goes quantitatively into the alkaline layer with a brown color. If 

 this is now shaken with water, the salt is dissociated and the Chlo- 

 rophyll is found unchanged in the ether. It will again respond to 

 the " brown-phase " test. The allomerized product does not give 

 the " brown-phase " test, f or a new and more stable lactam group- 

 ing is formed in the process of allomerization. 



Decomposition with acids. The action of acids, upon Chlo- 

 rophyll and the magnesium-containing derivatives obtained by the 

 action of alkali, consists in the quantitative removal of the com- 

 plexly bound magnesium and the Substitution of two atoms of hy- 

 drogen. The resulting products are free from mineral constituents. 

 By the mild action of acids the two ester groups of Chlorophyll are 

 not affected. In this reaction the color changes from green to 

 brown ; the resulting products are much more insoluble than are the 

 mother substances and this furnishes a convenient method for esti- 

 mating Chlorophyll derivatives : first, because of the greater insol- 

 ubility of the products and second, because these Compounds are 

 not as easily allomerized. 



The preparation of pheophytin-^ is best carried out by using a 

 90 percent alcoholic extract of Chlorophyll, which is shaken with a 

 conc. oxalic acid sol. or alcoholic hydrochloric acid at room tem- 

 perature. Four kilos of dry leaf meal are extracted with 6 liters of 

 90 percent alcohol, giving 4 liters of extract, the process taking 

 about 20 minutes. The extract is filtered and the filtrate from two 

 extractions united and treated with 160 c.c. of 10 percent alcoholic 

 hydrochloric acid. After standing an hour the pheophytin has 

 almost completely precipitated out. The mother liquor is decanted 

 and the precipitate filtered off, giving from 28 to 40 gm. of almost 



23 Willstätter and Hocheder: Ann. d. Cheni., 354, 2icS (1907). 



