510 CHEMISTRY OF THE PROTEIDS CHAP. 



bye-products are negligible, and with such reduced haemoglobin 

 15 per cent HC1 in the cold yields a pure haematoporphyrin. 

 Haematoporphyrin by uniting with iron becomes haemochromogen, 

 which by oxidation is changed into haematin, as will be shown later 

 (see p. 524). The formation of haematoporphyrin, using the old 

 formula for haematin (see p. 508) occurs readily and almost quanti- 

 tatively, according to the equation : l 



C 32 H 32 N 4 Fe0 4 + 2 H 2 + 2 HBr = 2C 16 H 18 N 2 3 + FeBr 2 + H 2 . 



Hsematin (one molecule) = Hsematoporphyrin (two molecules). 



Or using the new formula according to Zaleski : 2 



C 34 H 33 4 N 4 ClFe + 2 H 2 + 2 HBr - C 34 H 38 6 N 4 + FeBr 2 + HC1 



Hsemin (one molecule) = Hsematoporphyrin (one molecule). 



No hydrogen is given off during the formation of haematoporphyrin 

 according to Zaleski. 



Mesoporphyrin. On carefully reducing acet-hsemin or haemato- 

 porphyrin with hydriodic acid and phosphonium iodide, Nencki and 

 Zaleski obtained mesoporphyrin, to which they attributed the formula 

 C 16 H 18 N 2 2 . After Nencki's death his pupil Zaleski continued the 

 research, 3 and using a very detailed method has arrived at the result 

 that free mesoporphyrin has the formula 



Mesoporphyrin differs from haematoporphyrin in containing two oxygen 

 atoms less. Zaleski has prepared the following compounds of meso 

 porphyrin : 



C 34 H 38 4 N 4 . 2 HC1 Mesoporphyrin hydrochloride 



C 34 H 38 6 N 4 . 2 HC1 Haematoporphyrin hydrochloride 



C 34 H 36 4 N 4 . (C 2 H 5 ) 2 Mesoporphyrin ethylester 



C 34 H 36 4 N 4 . Zn Zinc (or Cu) salt of mesoporphyrin 



C 34 H 34 4 N 4 . (C 2 H 5 ) 2 Cu Copper salt of mesoporphyrin ethylester. 



Hcemopyrrol : Nencki and Zaleski, by further reduction of meso- 

 porphyrin with stronger hydriodic acid and more phosphonium 

 iodide, obtained haemopyrrol : 



C 8 H 13 N, 



1 M. Nencki and N. Sieber, Monatshefte f. Chemie, 9. 115 (1889) ; and in 

 Schmiedeberg's Archiv. fur experiment. Pathol. und Pharmakol. 24. 430 (1888) ; W. 

 Klister, Berichte d. deutsch. chem. Gesellscliaft, 30. I. 105 (1897). 



2 J. Zaleski, Zeitschr. /. physiol. Chem. 37. 74 (1902). 



3 J. Zaleski, ibid. 37. 54 (1902). 



