Iron protoporphyrin chloride

Table 13. Soret bands of protoporphyrin IX dimethylester iron(III) chloride in different solvents...

Protoporphyrin and its derivatives, because of their labile vinyl substituents, are susceptible to acid-catalyzed hydration. For this reason aqueous solutions should be avoided in the preparation of protoporphyrin dimethyl ester from protohemin, and subsequent reinsertion of the iron. Thus the direct esterification of protohemin under basic conditions appears to be the method of choice. More stable porphyrins such as H2oep are most conveniently prepared by the direct insertion of iron(lll) ion using the iron(III) chloride method5 the resultant Fe(IIl) (oep)Cl can be separated directly from the reaction medium as shining purple crystals. However, this method fails to give successful results with protoporphyrin derivatives. In general, the iron (II) sulfate method is the mildest and should be used for all prophyrins unless one is certain that the more rapid alternatives [boiling DMF with iron(II) chloride, or preferably the more stable iron(II) perchlorate] will have no ill effect on the peripheral substituents. 

In contrast to the case of inudazoles binding to tetraphenylporphyrins, Wang et have demonstrated that binding of cyanide to high-spin protoporphyrin IX iron(III) chloride in DMSO-c 6 is a two-step process as shown in equations (38) and (39), and whether DMSO acts as a sixth ligand for the mono-cyano complex is not known ... 

Caughey et a/. (1966) have done infrared studies of a series of substituted deutero-porphyrins IX (LXXXIV) which had been obtained from protoporphyrin IX or its iron(III) chloride (protohemin). These investigations have permitted vibrational... 

When hemin (1) is treated with gaseous hydrogen chloride in anhydrous methanol/pyridine in the presence of iron(II) sulfate, protoporphyrin dimethyl ester (2), the metal-free ligand of hemin. is produced in almost quantitative yield. This compound is quite sensitive to oxygen... 

Dimethyl protoporphyrinato(2-)iron(IIl), either as the chloride or the p-oxo dimer, is fairly soluble in chloroform and dichloromethane. The iron complex is much more stable toward light than the parent protoporphyrin but is still susceptible to acid-catalyzed hydration. The ester can be hydrolyzed to yield pure protohemin by using the alcoholic-KOH procedure.1,2 The optical spectra of these and other iron porphyrins have been reviewed recently.7... 

The arrangement of four nitrogen atoms in the center of the porphyrin ring enables porphyrins to chelate various metal ions. Protoporphyrin that contains iron is known as heme ferroheme refers specifically to the complex and ferri-heme to Fe. Ferriheme associated with a chloride counter ion is known as hemin, or hematin when the counter ion is hydroxide. 

Ferroheme is easily oxidized to ferriheme, containing iron(lll). Ferriheme chloride (old name hemin chloride) forms black crystals. Protoporphyrin is purple its color, the black color of hemin salts, and the red color of blood are related to the system of resonating double bonds in the porphyrin structure. 

Structure of the Haems.— The iron-porphyrans, or haems, like the other porphyrans are mono-metallic derivatives of a porphyrin. In haem the iron is ferrous (divalent) and united to one of the pyrrole nitrogens, conventionally regarded as belonging to ring I. In haematin (methaem) and in haematin chloride, the iron is ferric (trivalent) and united to two nitrogen atoms in the parent porphyran, protoporphyrin. 

Hsematoporphyrin, C3 H,gOgN4, an iron-free derivative of h m, is obtained by the action of strong acids on haemoglobin, or by dissolving haematin chloride in glacial acetic acid saturated with HBr. After four days, the mixture is diluted and the porphyrin precipitated by exact neutralisation. Haematoporphyrin is a dark violet powder, almost insoluble in water, but soluble in alcohol, alkalies, and concentrated sulphuric acid. It is a di-hydroxy derivative of Protoporphyrin, in which each vinyl side-chain, —CH CHg, has become —CHg.CHg.OH. 

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