256 VVillstättcr's Researches on Chlorophyll [Jan. 



Reduction of Chlorophyll derivatives. A further relation- 

 ship between the coloring matter of the blood and that of the green 

 plants is found in their behavior towards reducing agents. This 

 work was first undertaken by Nencki,^^ wlio isolated hemopyrrole 

 from both hemin and phylloporphyrine. Nencki's death occurred 

 shortly after the publication of this finding and the work was dis- 

 continued as a consequence. Work on the pyrroles obtained from 

 hemin was carried on later by Piloty^^ and Küster. ^^ They showed 

 that the reduction mixture probably consists of pyrroles and pyr- 

 rolines (reduced pyrroles), but thought pyrrole to be homogeneous. 

 The work of Willstätter and Asahina^^ showed that the products of 

 the reduction of the two classes of dyes were similar, but that a 

 complex mixture of pyrrole homologues was formed and not a 

 Single pyrrole, as has just been mentioned. 



The reduction was carried out essentially according to Nencki 

 and Zaleski. Twenty-five gm. of hemin were heated with a mix- 

 ture of 450 c.c. of acetic acid and 500 gm. of hydriodic acid (d. 

 1.96), 1.5 hours on a water-bath. After Solution was complete, 20 

 gm. of phosphonium iodide were added in small portions, in the 

 course of half an hour, the light yellow sol. then diluted with 1.5 

 vol. of water and anhydrous sodium carbonate added until the reac- 

 tion mixture was alkaline. The bases were distilled with steam, ex- 

 tracted with ether, and the ether sol. waslied with 30 percent mono- 

 sodium phosphate sol, which quantitatively removed the hydro- 

 genated pyrrole bases (secondary products of the reaction). 



More difficulty was found in separating the purified hemopyr- 

 role mixture. Fractional distillation in vacuum was of little use. 

 Fractional crystallization of the picrates did not yield good results. 

 Finally a satisfactory method was found in the fractional salt for- 

 mation with picric acid and, by the repeated use of this method, 

 three components were isolated, two of which, at least, were pure. 



The one which may not be pure is hemopyrrole, the picrate of 



3^ Nencki and Zaleski: Ber. d. deutsch, ehem. Gescllsch., 34, 997 (1901) ; 

 Nencki and Marchlewski : Ibid., 34, 1687 (1901). 



38 Piloty : Ann. d. Chem., 366, 237 (1909) ; 377, 314 (1910) ; Piloty and Quit- 

 mann: Ber. d. deutsch, ehem. Gesellsch., 42, 4693 (1909). 



39 Küster: Ann. d. Chem., 346, i (1906) ; Zeitschr. f. physiol. Chem., 55, 526 

 (1908). 



40 Willstätter and Asahina: Ann. d. Chem., 385, 188 (1911). 



