CONSTITUTION OF THE BLOOD-PIGMENTS. 297 



acid imide, which also hsemato- and mesoporphyrin give, were obtained by 

 MARCHLEWSKI on the oxidation of phylloporphyrin and by WILLSTATTER, 



/CO C.C 2 H 5 

 besides methylethylmaleic imide, HN<; , on the oxidation of 



X CO C.CH 3 



certain chlorophyll derivatives. The same two products were obtained 

 by KUSTER l on the oxidation of mesoporphyrin while hsemin and hsema- 

 to porphyrin gave no methylethylmaleic imide. 



It has been known for a long time that hsemin and hsematoporphyrin 

 gave an abundance of pyrrol on heating, and that phylloporphyrin has a 

 similar behavior was first shown by SCHUNCK and MARCHLEWSKI. 

 That at least one pyrrol, of the pyrrol mixture, the so-called hsemopyrrol 

 is common to both the blood and leaf pigments has been shown by the 

 investigations of MARCHLEWSKI and his collaborators, and from hsemo- 

 pyrrol KUSTER was the first to obtain methylethylmaleic imide on oxida- 

 tion, showing that hsemopyrrol was probably a dimethylethylpyrrol. 

 This behavior has been further developed by the investigations of 

 PILOTY and WILLSTATTER on the reduction products of the blood and 

 leaf pigments and by H. FISCHER and BARTHOLOMAUS 2 on the sub- 

 stituted pyrrols. 



WILLSTATTER obtained a pyrrol mixture from hsemin and hsemato- 

 porphyrin, as well as from chlorophyll derivatives, by reduction, from 

 which he isolated three different pyrrols. The first, which he calls hoemo- 

 pyrrol, was perhaps not perfectly pure, consisted at least in great part 

 of the cryptopyrrol (FISCHER and BARTHOLOMAUS. c-hsemopyrrol of 

 PILOTY and STOCK) which is identical with the 2, 4-dimethyl-3-ethyl 



H 3 C.C- -C.CoH 5 

 pyrrol = || prepared synthetically by KNORR and HESS. S 



HC NH C.CH 3 



The second hsemopyrrol, which he calls isohcemopyrrol ( = hsemopyrrol 

 of FISCHER and BARTHOLOMAUS, B-hsemopyrrol of PILOTY and STOCK) 

 is also a trisubstituted pyrrol, namely 2, 3-dimethyl-4-ethylpyrfol 



C 2 H 5 .C- C.CH 3 



II II 



HC NH C.CH 3 

 These two dimethylethylpyrrols give with nitrous acid the correspond- 



1 Ber. d. d. chem. Gesellsch., 45. 



2 Piloty, Annal. d. Chem. u. Pharm., 377, 388, 390, and 392; Willstatter and 

 Asahina, ibid., 385. In this article will be found on pages 189 and 190 the references 

 to the literature on the investigations of Marchlewski and others on hsemopyrrol. 

 H. k Fischer and Bartholomaus, Zeitschr. f. physiol. Chem., 77 and 80 and Ber. d. d. 

 chem. Gesellsch., 45. 



3 Piloty and Stock, Annal. d. Chem. u. Pharm., 392; Knorr and Hess, Ber. d. 

 d. chem. Gesellsch., 44 and 45. 



