The Structure of Porphyrin a, Cryptoporphyrin a and Chlorin ag 351 



IX if formula II is correct, but another porphyrin with two methyl groups on 

 one pyrrole from a porphyrin of formula I. The results are as yet inconclusive. 

 The dimethyl porphyrin ester obtained greatly resembled deuteroporphyrin 

 IX ester, and gave no melting point depression with it, but had a lower melting 

 point (203-206° compared with 220-222° of the deuteroporphyrin ester). 



Large A Iky I Group (or Groups) and Molecular Weight of Porphyrin 



The molecular weight of porphyrin a can be calculated from the analyses 

 of haemin a, in particular its iron content (Table 4), and from the ratio of 

 molar extinction to specific extinction of pyridine haemochrome a and 

 porphyrin a. While these results are as yet not fully concordant (Table 5), 

 they show that the molecular weight is considerably greater than that of 

 protoporphyrin and that R^ + R2 of the formulae in Fig. 3 is between 



Table 5. Molecular weight of porphyrin a and size of R groups 



{R, + R,) 



M.W. of porphyrin 



Additional C atoms 



Warburg haemin analyses 

 Lemberg haemin analyses 

 Pyridine haemochrome a, fji/^s 

 Porphyrin a, fji/^sp 



760-790 

 835-860 

 740-810 



< 875 



12-14 

 16-18 

 11-16 

 <20 



C12H25 and C20H41. These alkyl groups or group can only be attached to the 

 vinyl and the a-hydroxylalkyl, since they are removed in the resorcinol melt. 

 Some of it at least, must be attached to the vinyl since no crystalline porphyrin 

 was obtained in the resorcinol melt after catalytic hydrogenation of the 

 unsaturated group. 



Since we have observed that an acetyl group is not removed by milder 

 conditions in the resorcinol melt, we hope to solve the problem whether the 

 group resulting from oxidation of the a-hydroxyalkyl group is acetyl or a 

 substituted acetyl group. 



We have so far refrained from an attempt to obtain information by an 

 oxidation of porphyrin a and the attempt at isolation of the fatty acid or acids, 



